Ink composition, ink set and recording method

ABSTRACT

An ink composition, which comprises: at least two kinds of water-soluble dyes each having the maximum wavelength of an absorption spectrum in an aqueous solvent of from 550 to 700 nm, wherein at least one of the at least two kinds of water-soluble dyes is selected from the group consisting of a compound represented by formula (L-1) as defined in the specification, a salt of the compound represented by formula (L-1) and a compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups; an ink set containing at least one kind of the ink composition; a recording method comprising applying the ink composition to a recording medium; and a recording method comprising loading the ink set on a recording apparatus, and applying the ink from the recording apparatus to a recording medium.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ink composition, an ink set, and a recording method, in particular, relates to an ink composition capable of forming an image having high fastness and high density.

2. Description of the Related Art

With the spread of the computer in recent years, ink jet printers have been widely used not only in offices but also in homes for printing on papers, films and cloths.

As ink jet recording methods, a method of ejecting ink droplets by applying pressure by piezo-elements, a method of ejecting ink droplets by generating bubbles in ink by heat, a method of using ultrasonic waves, and a method of suction ejection of ink droplets by electrostatic force are known. As the ink compositions for these ink jet recordings, water ink, oil ink and solid ink (a melting type) are used. Of these inks, water ink is mainly used for easiness of manufacture and handling, odors and safety.

Colorants used in inks for these ink jet recordings are required to have high solubility in solvents, to be capable of high density recording, to be good in hue, to be excellent in fastness to light, heat, air, water and chemicals, to have good fixing property to image-receiving materials and to hardly blot, to be excellent in preservation property as inks, to be free of toxicity, to be high in purity, and to be available inexpensively. However, it is extremely difficult to search for colorants that satisfy these requirements in high levels.

Various dyes and pigments have been already proposed for ink jet recording and practically used but colorants satisfying all of these requirements have not been discovered yet. It is difficult for conventionally known dyes and pigments having Color Index Nos. (C.I.) to reconcile the hue and fastness required of the inks for ink jet recording.

Tris-azo dyestuffs and tetrakis-azo dyestuffs arc discussed in recent years as the dyes for black inks and disclosed in JP-A-2005-220211 (the term “JP-A” as used herein refers to an “unexamined published Japanese patent application”), JP-A-2004-28535 1, JP-A-2005-2271 and WO 03/106572, but these dyestuffs do not come to sufficiently satisfy the demands of the market, in particular on the fastness to gases and lights.

The present inventors have continued the examination of dyes good in hue and fastness and the development of dyes excellent for ink jet recording. From these examinations, it has been found, as disclosed in JP-A-2005-162823, that it is effective to use a dye high in association to increase fastness of images.

However, it has also been found that, when a dye having an associating property is used, there arise problems of liability to bronzing (abnormal glossiness) at the high concentration area, and the reduction of image density as compared with a dye not having an associating property.

SUMMARY OF THE INVENTION

An object of the invention is to provide a black ink composition for ink jet recording that is capable of excellent black tone and high density printing, excellent in image fastness, capable of restraining bronze glossiness, free of blotting, and excellent in discoloration balance, another object is to provide an ink set containing the same, and a further object is to provide a recording method using the same.

(1) An ink composition, which comprises:

at least two kinds of water-soluble dyes each having the maximum wavelength of an absorption spectrum in an aqueous solvent of from 550 to 700 nm,

wherein at least one of the at least two kinds of water-soluble dyes is selected from the group consisting of a compound represented by formula (L-1), a salt of the compound represented by formula (L-1) and a compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups:

wherein A and B each independently represents an aromatic group that may be substituted or a heterocyclic group that may be substituted, and A is a monovalent group and B is a divalent group;

T₁ and T₂ each independently represents ═CR₄₃— or —CR₄₄═, or either one represents a nitrogen atom and the other represents ═CR₄₃— or —CR₄₄═;

V₁, R₄₃ and R₄₄ each independently represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclic oxycarbonyl group, an acyl group, a hydroxyl group, an alkoxyl group, an aryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, an amino group, an acylamino group, a ureido group, a sulfamoylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylsulfonylamino group, an alkylsulfonylamino group, a heterocyclic sulfonylamino group, a nitro group, an alkylthio group, an arylthio group, a heterocyclic thio group, an alkylsulfonyl group, an arylsulfonyl group, a heterocyclic sulfonyl group, an alkylsulfinyl group, an arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group or a sulfo group, and each of these groups may further be substituted;

R₄₁, R₄₂, R₄₃ and R₄₄ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a heterocyclic group, all acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group or a sulfamoyl group, and each of these groups may further have a substituted, provided that R₄₁ and R₄₂ do not represent a hydrogen atom at the same time, and R₄₃ and R₄₁, or R₄₂, and R42 may be bonded to each other to form a 5- or 6-membered ring, provided that the compound represented by formula (L-1) contains at least one ionic hydrophilic group.

(2) The ink composition as described in (1) above,

wherein the compound represented by formula (L-1) is a compound represented by formula (L-2):

wherein X represents an N atom or ═CW₁—;

W₁ represents an electron attracting group having a Hammett's substitution constant op value of 0.20 or more;

A, V₁, T₁, T₂, R₄₁, and R₄₂ respectively have the same meaning as A, V₁, T₁, T₂, R₄₁ and R₄₂ in formula (L-1); and

W has the same meaning as VI in formula (L-1).

(3) The ink composition as described in (1) or (2) above,

wherein the compound represented by formula (L-2) is a compound represented by formula (L-3):

wherein V₁, W, X, T₁, T₂, R₄₁ and R₄₂ respectively have the same meaning as V₁, W, X, T₁, T₂, R₄, and R₄₂ in formula (L-2); and

X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each represents a monovalent group.

(4) The ink composition as described in any of (1) to (3) above, which comprises at least one compound represented by formula (L-1) and at least one compound represented by formula (L-4) different in structure from each other:

wherein R₄₃ has the same meaning as R₄₃ in formula (L-1);

R₄₄ has the same meaning as R₄₄ in formula (L-1);

R₄₅ and R₄₆ each has the same meaning as R₄₁ and R₄₂ in formula (L-1);

R₄₁ and R₄₂ each has the same meaning as R₄₁ and R₄₂ in formula (L-1);

W has the same meaning as V₁ in formula (L-1); and

X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each represents a monovalent group.

(5) The ink composition as described in any of (1) to (3) above, which comprises at least one compound represented by formula (L-1) and at least one compound represented by formula (L-5) different in structure from each other:

wherein R₄₃ has the same meaning as R₄₃ in formula (L-1);

R₄₄ has the same meaning as R in formula (L-1);

R₄₅ and R₄₆ each has the same meaning as R₄₁ and R₄₂ in formula (L-1);

R₄₁ and R₄₂ each has the same meaning as R₄₁ and R₄₂ in formula (L-1);

W has the same meaning as V₁ in formula (L-1);

W₁₁ represents an electron attracting group having a Hammett's substitution constant op value of 0.20 or more; and

X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each represents a monovalent group.

(6) The ink composition as described in any of (l) to (5) above,

wherein the number of azo groups of the compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups is five or less.

(7) The ink composition as described in any of (1) to (6) above,

wherein the compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups contains one or more sulfonic acid group(s), one or more carboxyl group(s), or one or more sulfonic acid group(s) and one or more carboxyl group(s).

(8) The ink composition as described in any of (1) to (7) above,

wherein the compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups is a compound selected from the group consisting of a compound represented by any of formulae (L-6), (L-6a), (L-7) and (L-8) and a salt of the compound represented by any of formulae (L-6), (L-6a), (L-7) and (L-8):

wherein R₁₁ and R₁₂ each independently represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a sulfamoyl group that may be substituted with an alkyl group or a phenyl group; a phosphoric acid group; a nitro group; an acyl group; a ureido group; an alkyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group or an alkoxyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms or an acylamino group that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group or a carboxyl group;

E represents a phenyl group or a naphthyl group, which may be substituted with a halogen atom; a cyano group; a carboxyl group; a sulfo group; a sulfamoyl group that may be substituted with an alkyl group or a phenyl group; a phosphoric acid group; a nitro group; an acyl group; a ureido group; an alkyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group or an alkoxyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms or an acylamino group that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group or a carboxyl group; and

n₁ represents 0 or 1;

wherein A represents formula (L-6a-1), and the substitution position of A is the m- or p-position to the azo group;

R¹ and R² each independently represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a sulfamoyl group; an N-alkylaminosulfonyl group; an N-phenylamino-sulfonyl group; a phospho group; a nitro group; an acyl group; a ureido group; an alkyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group or an alkoxyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group or a carboxyl group; or an acylamino group that may be substituted with an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group or a carboxyl group;

R³ and R⁴ each independently represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a nitro group; an alkyl group having from 1 to 4 carbon atoms; a hydroxyl group; or an alkoxyl group having from 1 to 4 carbon atoms that may be substituted with an alkoxyl group having from 1 to 4 carbon atoms or a sulfo group; and

n represents 0 or 1;

wherein R⁵ represents a cyano group; a carboxyl group; an alkyl group having from 1 to 4 =carbon atoms; an alkoxycarbonyl gruop having from 1 to 4 carbon atoms; or a phenyl group;

R⁶, R⁷ and R⁸ each independently represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a nitro group; an alkyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms that may be substitutted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms or a sulfo group; or an acylamino group that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms or a sulfo group;

wherein G and J each independently represents a phenyl group or a naphthyl group that may be substituted, or a 5- or 6-membered aromatic heterocyclic group bonding to the azo group via a carbon atom, and each of G and J contains at least one or more carboxyl group(s) or sulfo group(s);

one of X and Y represents a hydroxyl group, and the other represents an amino group; and

l₂, m₂ and n₂ each independently represents 1 or 2;

wherein R₂₁ represents a phenyl group having a substituent, or a naphthyl group having a substituent;

R₂₂ represents a phenylene group having a substituent, or a naphthylene group having a substituent;

R₂₃ represents a 5- to 7-membered heterocyclic group having at least one double bond and a substituent; and

the substituents in R₂₁, R₂₂ and R₂₃ are each independently selected from the group consisting of OH, SO₃H, PO₃H₂, CO₂H, NO₂, NH₂, an alkyl group having from 1 to 4 carbon atoms, an alkyl group having from 1 to 4-carbon atoms and a substituent, an alkoxyl group having from 1 to 4 carbon atoms, an alkoxyl group having from 1 to 4 carbon atoms and a substituent, an amino group, an amino group having a substituent and a phenyl group having a substituent.

(9) An ink composition, which comprises:

at least two kinds of water-soluble dyes each having the maximum wavelength of an absorption spectrum in an aqueous solvent of from 550 to 700 nm,

wherein the at least two kinds of water-soluble dyes include: at least one compound selected from the group consisting of a compound represented by formula (L-1) according to claim 1, a compound represented by formula (L-2) according to claim 2, a compound represented by formula (L-3) according to claim 3, a compound represented by formula (L-4) according to claim 4 and a compound represented by formula (L-5) according to claim 5; and at least one compound selected from the group consisting of a compound represented by any of formulae (L-6), (L-6a), (T-7) and (L-8) and a salt of the compound represented by any of formulae (L-6), (L-6a), (L-7) and (L-8) according to claim 8.

(10) The ink composition as described in (8) or (9) above,

wherein the compound represented by formula (L-8) is a compound represented by formula (L-9):

wherein R₃₁ to R₃₉ each independently represents a group selected from the group consisting of H, OH, SO₃H, PO₃H₂, CO₂H, NO₂ and NH₂.

(11) The ink composition as described in any of (1) to (10) above, which further comprises at least one kind of water-soluble dye having the maximum wavelength of an absorption spectrum in an aqueous solvent of from 400 to 520 nm.

(12) The ink composition as described in (11) above, which comprises the at least one kind of water-soluble dye having the maximum wavelength of an absorption spectrum in an aqueous solvent of from 400 to 520 nm in an amount of from 0.1 to 4 mass %.

(13) An ink set, which comprises at least one kind of an ink composition as described in any of (1) to (12) above.

(14) A recording method, which comprises:

applying an ink composition as described in any of (1 ) to (12) above to a recording medium to conduct recording.

(15) A recording method, which comprises:

loading an ink set as described in (13) above on a recording apparatus; and

applying an ink from the recording apparatus to a recording medium to conduct recording.

(16) The recording method as described in (14) or (15) above, which comprises:

ejecting the ink composition from an ink jet nozzle to a recording medium to conduct recording.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in detail below.

The ink composition according to the invention contains at least two kinds of water-soluble dyes having the maximum wavelength of an absorption spectrum in an aqueous solvent of from 550 to 700 nm (hereinafter referred to as “water-soluble long wave dyes L”), and at least one of the water-soluble dyes is selected from the group consisting of a compound represented by the following formula (L-1), a salt thereof, and a compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups. The ink composition according to the invention is preferably used as black ink.

Water-Soluble Long Wave Dye L:

Water-soluble long wave dye L in the invention has the maximum of an absorption spectrum (the absorption maximum) in an aqueous solvent of from 550 to 700 nm. The maximum of an absorption spectrum (the absorption maximum) in an aqueous solvent of water-soluble long wave dye L is preferably from 560 to 680 nm, and more preferably from 570 to 650 nm. It is preferred for these absorption spectra to have broad absorption in a visible region, and the hue is preferably black, not bright hues such as magenta and cyan. The half value width of the absorption spectra is preferably 100 nm or more (more preferably from 120 to 500 nm, and still more preferably from 120 to 350 nm). Here, an aqueous solvent means a medium comprising water as the main solvent and may contain an appropriate amount of a water-miscible organic solvent capable of dissolving or dispersing a dye. Further, an absorption spectrum means an absorption spectrum that is measured with a usually used spectrophotometer using a cell of 1 cm. These are also the same as in the later-described water-soluble short wave dye S.

The absorption spectrum of water-soluble long wave dye L is an absorption spectrum measured with a single compound. That is, when an absorption spectrum in an aqueous solvent is measured, water-soluble long wave dye L in the invention means to show the physical properties such as the desired absorption maximum and half value width not by combining a plurality of compounds but to show these physical properties by a single compound. Incidentally, it is apparent in the invention that as water-soluble long wave dyes L (hereinafter also referred to as “long wave dye L”), compounds having structures different from each other may be used in combination so long as they satisfy the absorption spectra. Further, in the invention, dyes other than long wave dye L having the absorption spectrum characteristics may be used in combination.

Further, as long wave dye L, a dye having such properties as capable of association and whose reaction can be physically controlled is more preferred.

Whether a dye is in an association state or not can be easily judged by the measurement of visible absorption spectra by changing the concentration of the dye, and judging whether the dye has an associating property or not by the examination of the absorption maximum wavelength, the molar absorption coefficient and the change of wave form, and comparing these solution physical properties and the absorption spectra of the dye on an image-receiving material.

Specifically, a preferred dye is a dye that forms the relationship of ε1/ε2>1.2 between the molar absorption coefficient (ε1) in the maximum wavelength of visible region absorption at the time when 0.1 mmol/liter of a dye aqueous solution is measured with a cell of optical path length of 1 cm as defined in JP-A-2004-307831, and the molar absorption coefficient (ε2) at the time when 0.2 mol/liter of the aqueous solution is measured with a liquid crystal cell of optical path length of 5 μm.

In the invention, as long wave dye L, at least one compound selected from the group consisting of a compound represented by the following formula (L-1), a salt thereof, and a compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups is contained.

In the following formula, the dye is shown as a free acid structure, but of course the dye may be used in the form of a salt in practical use.

In formula (L-1), A and B each represents an aromatic group that may be substituted, or a heterocyclic group that may be substituted (A is a monovalent group and B is a divalent group).

T₁ and T₂ each represents ═CR₄₃— or —CR₄₄═, or either one represents a nitrogen atom and the other represents ═CR₄₃— or —CR₄₄═. V₁, R₄₃ and R₄₄ each represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclic oxycarbonyl group, an acyl group, a hydroxyl group, an alkoxyl group, an aryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, an amino group (in this specification, the meaning of an amino group includes not only an unsubstituted amino group but also an alkylamino group, an arylamino group and a heterocyclic amino group), an acylamino group, a ureido group, a sulfamoylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a heterocyclic sulfonylamino group, a nitro group, an alkylthio group, an arylthio group, a heterocyclic thio group, an alkylsulfonyl group, an arylsulfonyl group, a heterocyclic sulfonyl group, an alkylsulfinyl group, an arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group, or a sulfo group, and each of these groups may further be substituted. R₄₁, R₄₂, R₄₃ and R₄₄ each represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, or a sulfamoyl group, and each of these groups may further have a substituted, provided that R₄₁ and R₄₂ do not represent a hydrogen atom at the same time, and R₄₃ and R₄₁, or R₄₁, and R₄₂ may be bonded to each other to form a 5- or 6-membered ring.

Formula (L-1) will be described in detail below below.

In formula (L-1), A preferably represents a monovalent aromatic group that may be substituted, or a monovalent heterocyclic group that may be substituted, more preferably a substituted phenyl group, a substituted naphthyl group, or a substituted or unsubstituted heterocyclic group, and of these, a phenyl group and a naphthyl group substituted with an ionic hydrophilic group, and a 5- or 6-membered nitrogen-containing heterocyclic ring having a substituent are preferred, in particular a phenyl group and a naphthyl group substituted with a sulfo group (including the salts thereof) or a carboxyl group (including the salts thereof) are preferred, and a phenyl group and a naphthyl group substituted with 2 or more sulfo groups (including the salts thereof) or carboxyl groups (including the salts thereof) are more preferred, and a naphthyl group substituted with 2 or 3 sulfo groups (including the salts thereof) is most preferred.

In formula (L-1), B represents a divalent aromatic group that may be substituted or a divalent heterocyclic group that may be substituted, more specifically B preferably represents a 5- or 6-membered heterocyclic group having a substituent, and a 5-membered heterocyclic group having a substituent is more preferred. The 5- or 6-membered heterocyclic ring means a 5- or 6-membered ring containing a hetero atom. As the hetero atom of the heterocyclic ring, N, S and O atoms are exemplified.

The heterocyclic ring represented by B may be condensed with an aliphatic group, an aromatic ring, or other heterocyclic ring, and the heterocyclic ring may have a substituent on the condensed ring. The heterocyclic ring represented by B means both a saturated heterocyclic ring and an unsaturated heterocyclic ring, and an unsaturated heterocyclic ring is preferred. In the case of a nitrogen-containing heterocyclic ring, the N atom may be quaternized. Further, with respect to a heterocyclic ring of tautomerism, when one alone of tautomers is described, it also includes the other tautomer.

As especially preferred heterocyclic rings represented by B, a pyridine ring, a pyrazine ring a pyrimidine ring, a pyridazine ring, a thiophene ring, a thiazole ring, an imidazole ring, a benzothiazole ring, and a thienothiazole ring are exemplified.

In formula (L-1), T₁ and T₂ each represents ═CR₄₃— or —CR₄═, or either one represents a nitrogen atom and the other represents ═CR₄₃— or —CR₄₄═, but the case where T₁ and T₂ each represents ═CR₄₃— or —CR₄₄═ is preferred for the reason of capable of exhibiting more excellent performance.

In formula (L-1), R₄₁ and R₄₂ each represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, or a sulfamoyl group, and each of these groups may further have a substituted. Of these groups, a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, an acyl group, an alkylsulfonyl group, and an arylsulfonyl group are preferred, further, a hydrogen atom, an alkyl group, an aryl group, and a heterocyclic group are more preferred, a hydrogen atom, an aryl group having a substituent, and a heterocyclic group having a substituent are especially preferred, and a hydrogen atom and an aryl group having a substituent are most preferred. However, R₄₁ and R₄₂ do not represent a hydrogen atom at the same time, and R₄₃ and R₄₁, or R₄₁, and R₄₂ may be bonded to each other to form a 5- or 6-membered ring.

In formula (L-1), V₁ preferably represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a heterocyclic group, a hydroxyl group, an alkoxyl group, an, aryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxy group, an amino group (including an alkylamino group, an arylamino group, and a heterocyclic amino group), an acylamino group, a ureido group, a sulfamoylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylthio group, an arylthio group, or a heterocyclic thio group, and each of these groups may further be substituted.

V₁ more preferably represents a hydrogen atom, a halogen atom, an alkyl group, a hydroxyl group, an alkoxyl group, an aryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxy group, an amino group (including an alkylamino group, an arylamino group, and a heterocyclic amino group), or an acylamino group. Of these groups, a hydrogen atom, an amino group (including an alkylamino group, an arylamino group, and a heterocyclic amino group), and an acylamino group are preferred, an amino group having a substituent is especially preferred, and an amino group substituted with an aryl group having an ionic hydrophilic group as the substituent (e.g., a substituted anilino group, etc.) is most preferred.

The ionic hydrophilic groups include a sulfo group, a carboxyl group, a phosphono group, a quaternary ammonium group, etc. As the ionic hydrophilic groups, a carboxyl group, a phosphono group, and a sulfo group are preferred, a carboxyl group and a sulfo group are especially preferred, and a sulfo group is most preferred from the viewpoint of increasing solubility in an aqueous solvent. A carboxyl group, a phosphono group, and a sulfo group may be in the state of a salt, and the examples of the counter salts include ammonium, alkali metal (e.g., lithium, sodium, potassium), and organic cation (e.g., tetramethylammonium, tetramethylguanidinium, tetramethylphosphonium). As the counter salts, ammonium, lithium, sodium and potassium are preferred, sodium and lithium are more preferred, and lithium is most preferred.

The especially preferred combinations as the compounds represented by formula (L-1) are combinations containing the following (a) to (e).

-   (a) A preferably represents a substituted phenyl group, a     substituted naphthyl group, or a substituted or unsubstituted     heterocyclic group, and of these, a phenyl group and a naphthyl     group substituted with an ionic hydrophilic group, and a 5- or     6-membered nitrogen-containing heterocyclic ring having a     substituent are preferred, in particular a phenyl group and a     naphthyl group substituted with a sulfo group (including the salts     thereof) or a carboxyl group (including the salts thereof) are     preferred, a phenyl group and a naphthyl group substituted with 2 or     more sulfo groups (including the salts thereof) or carboxyl groups     (including the salts thereof) are more preferred, and a naphthyl     group substituted with 2 or 3 sulfo groups (including the salts     thereof) is most preferred. -   (b) B preferably represents a 5- or 6-membered heterocyclic group     having a substituent, and a 5-membered heterocyclic group having a     substituent is more preferred As especially preferred heterocyclic     rings, a pyridine ring, a pyrazine ring a pyrimidine ring, a     pyridazine ring, a thiophene ring, a thiazole ring, an imidazole     ring, a benzothiazole ring, and a thienothiazole ring are     exemplified. -   (c) T, and T₂ each represents ═CR₄₃— or —CR₄₄═, or either one     represents a nitrogen atom and the other represents ═CR₄₃— or     —CR₄₄═, but the case where T₁ and T₂ each represents ═CR₄₃— or     —CR₄₄═ is preferred for the reason of capable of exhibiting more     excellent performance. -   (d) R₄₁ and R₄₂ each preferably represents a hydrogen atom, an alkyl     group, an aryl group, a heterocyclic group, an acyl group, an     alkylsulfonyl group, or an arylsulfonyl group, more preferably a     hydrogen atom, an alkyl group, an aryl group, or a heterocyclic     group, especially preferably a hydrogen atom, an aryl group having a     substituent, or a heterocyclic group having a substituent, and most     preferably a hydrogen atom or an aryl group having a substituent.     However, R₄₁ and R₄₂ do not represent a hydrogen atom at the same     time, and R₄₃ and R₄₁, or R₄₁ and R₄₂ may be bonded to each other to     form a 5- or 6-membered ring. -   (e) V₁ represents a hydrogen atom, a halogen atom, an alkyl group, a     hydroxyl group, an alkoxyl group, an aryloxy group, a heterocyclic     oxy group, a silyloxy group, an acyloxy group, an amino group     (including an alkylamino group, an arylamino group, and a     heterocyclic amino group), or an acylamino group, preferably a     hydrogen atom, an amino group (including an alkylamino group, an     arylamino group, and a heterocyclic amino group), or an acylamino     group, especially preferably an amino group having a substituent,     and most preferably an amino group substituted with an aryl group     having an ionic hydrophilic group as the substituent (e.g., a     substituted anilino group, etc.).

Regarding combination of the preferred substituents of the dyestuff represented by formula (L-1), a compound wherein at least one of various substituents is the above preferred group is preferred, a compound wherein more substituents of various substituents are the above preferred groups is more preferred, and a compound wherein all the substituents are the preferred groups is most preferred.

The compound represented by formula (L-1) is preferably a compound represented by the following formula (L-2).

In formula (L-2), X represents an N atom or ═CW₁—; W₁ represents an electron attracting group having a Hammett's substitution constant σp value of 0.20 or more; A, V₁, T₁, T₂, R₄₁ and R₄₂ respectively have the same meaning as A, V₁, T₁, T₂, R₄₁ and R₄₂ in formula (L-1); and W has the same meaning as V₁ in formula (L-1).

Formula (L-2) will be described in detail below.

In formula (L-2), W preferably represents a substituted phenyl group, a substituted or unsubstituted naphthyl group, or a substituted or unsubstituted heterocyclic group (e.g., a pyrrole ring, a thiophene ring, an imidazole ring, a thiazole ring, a benzothiazole ring, a pyridine ring, or a pyridazine ring), and especially preferably a substituted phenyl group (in particular, a phenyl group substituted at the para-position), a substituted or unsubstituted β-naphthyl group, a pyridine ring, or a thiazole ring.

In formula (L-2), X represents an N atom or ═CW₁—, W₁ represents an electron attracting group having a Hammett's substitution constant σp value of 0.20 or more. An electron attracting group having a up value of 0.30 or more is preferred, 0.45 or more is more preferred, and 0.60 or more is especially preferred, but it is desired that the Hammett's substitution constant op value does not exceed 1.0. More specifically, W₁ preferably represents an acyl group having from 2 to 20 carbon atoms, an alkyloxycarbonyl group having from 2 to 20 carbon atoms, a nitro group, a cyano group, an alkylsulfonyl group having from 1 to 20 carbon atoms, an arylsulfonyl group having from 6 to 20 carbon atoms, a carbamoyl group having from 1 to 20 carbon atoms, or a halogenated alkyl group having from 1 to 20 carbon atoms, especially preferably represents a cyano group, an alkylsulfonyl group having from I to 20 carbon atoms, or an arylsulfonyl group having from 6 to 20 carbon atoms, and most preferably a cyano group.

In formula (L-2), A has the same meaning as A in formula (L-1), and the preferred examples are also the same.

In formula (L-2), T₁ and T₂ each has the same meaning as T₁ and T₂ in formula (L-1), and the preferred examples are also the same.

In formula (L-2), R₄₁ and R₄₂ each has the same meaning as R₄₁ and R₄₂ in formula (L-1), and the preferred examples are also the same.

In formula (L-2), V₁ has the same meaning as V₁ in formula (L-1), and the preferred examples are also the same.

The especially preferred combinations as the compounds represented by formula (L-2) are combinations containing the following (a) to (f).

-   (a) W preferably represents a substituted phenyl group, a     substituted or unsubstituted naphthyl group, or a substituted or     unsubstituted heterocyclic group (e.g., a pyrrole ring, a thiophene     ring, an imidazole ring, a thiazole ring, a benzothiazole ring, a     pyridine ring, or a pyridazine ring), and especially preferably a     substituted phenyl group (in particular, a phenyl group substituted     at the para-position), a substituted or unsubstituted β-naphthyl     group, a pyridine ring, or a thiazole ring. -   (b) X represents an N atom or ═CW₁—, and W₁ represents an electron     attracting group having a Hammett's substitution constant σp value     of 0.20 or more. More specifically, W₁ preferably represents an acyl     group having from 2 to 20 carbon atoms, an alkyloxycarbonyl group     having from 2 to 20 carbon atoms, a nitro group, a cyano group, an     alkylsulfonyl group having from 1 to 20 carbon atoms, an     arylsulfonyl group having from 6 to 20 carbon atoms, a carbamoyl     group having from 1 to 20 carbon atoms, or a halogenated alkyl group     having from 1 to 20 carbon atoms, especially preferably a cyano     group, an alkylsulfonyl group having from 1 to 20 carbon atoms, or     an arylsulfonyl group having from 6 to 20 carbon atoms, and most     preferably a cyano group. -   (c) A preferably represents a substituted phenyl group, a     substituted naphthyl group, or a substituted or unsubstituted     heterocyclic group, and more preferably a phenyl group or a naphthyl     group substituted with an ionic hydrophilic group, or a 5- or     6-membered nitrogen-containing heterocyclic ring having a     substituent, especially preferably a phenyl group or a naphthyl     group substituted with a sulfo group (including the salts thereof)     or a carboxyl group (including the salts thereof), and still more     preferably a phenyl group or a naphthyl group substituted with 2 or     more sulfo groups (including the salts thereof) or carboxyl groups     (including the salts thereof), and most preferably a naphthyl group     substituted with 2 or 3 sulfo groups (including the salts thereof). -   (d) T₁ and T₂ each represents ═CR₄₃— or —CR₄₄═, or either one     represents a nitrogen atom and the other represents ═CR₃— or —CR₄₄═,     but the case where T₁ and T₂ each represents ═CR₄₃— or —CR₄₄═ is     preferred for the reason of capable of exhibiting more excellent     performance. -   (e) R₄₁ and R₄₂ each preferably represents a hydrogen atom, an alkyl     group, an aryl group, a heterocyclic group, an acyl group, an     alkylsulfonyl group, or an arylsulfonyl group, more preferably a     hydrogen atom, an alkyl group, an aryl group, or a heterocyclic     group, especially preferably a hydrogen atom, an aryl group having a     substituent, or a heterocyclic group having a substituent, and most     preferably a hydrogen atom or an aryl group having a substituent.     However, R₄₁ and R₄₂ do not represent a hydrogen atom at the same     time, and R₄₃ and R₄₁, or R₄₁ and R₄₂ may be bonded to each other to     form a 5- or 6-membered ring. -   (f) V, represents a hydrogen atom, a halogen atom, an alkyl group, a     hydroxyl group, an alkoxyl group, an aryloxy group, a heterocyclic     oxy group, a silyloxy group, an acyloxy group, an amino group     (including an alkylamino group, an arylamino group, and a     heterocyclic amino group), or an acylamino group, preferably a     hydrogen atom, an amino group (including an alkylamino group, an     arylamino group, and a heterocyclic amino group), or an acylamino     group, especially preferably an amino group having a substituent,     and most preferably an amino group substituted with an aryl group     having an ionic hydrophilic group as the substituent (e.g., a     substituted anilino group, etc.).

Regarding combination of the preferred substituents of the dyestuff represented by formula (L-2), a compound wherein at least one of various substituents is the above preferred group is preferred, a compound wherein more substituents of various substituents are the above preferred groups is more preferred, and a compound wherein all the substituents arc the preferred groups is most preferred.

The compound represented by formula (L-2) is preferably a compound represented by the following formula (L-3).

In formula (L-3), V₁, W, X, T₁, T₂, R₄₁ and R₄₂ respectively have the same meaning as V₁, W, X, T₁, T₂, R₄₁ and R₄₂ in formula (L-2), and X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each has the same meaning as V₁ in formula (L-1).

Formula (L-3) will be described in detail below.

In formula (L-3), the monovalent group represented by X₁, X₂, X₃, X₄, X5, X₆ and X₇ is a hydrogen atom or a monovalent substituent. The monovalent substituent will be described in further detail. The examples of the monovalent substituents include a halogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a cyano group, a hydroxyl group, a nitro group, an alkoxyl group, an aryloxy group, a silyloxy group, a heterocyclic oxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, an aryloxy-carbonyloxy group, an amino group (an alkylamino group, an arylamino group), an acylamino group (an amido group), an aminocarbonylamino group (a ureido group), an alkoxycarbonyl-amino group, an aryloxycarbonylamino group, a sulfamoylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, an alkylthio group, an arylthio group, a heterocyclic thio group, a sulfamoyl group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group, an aryloxycarbonyl group, an alkoxy-carbonyl group, a carbamoyl group, a phosphino group, a phosphinyl group, a phosphinyloxy group, a phosphinylamino group, a silyl group, an azo group, and an imido group, and each of these groups may further have a substituent.

X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each preferably represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a heterocyclic group, a cyano group, an alkoxyl group, an amido group, a ureido group, an alkylsulfonylamino group, an arylsulfonylamino group, a sulfamoyl group, an alkylsulfonyl group, an arylsulfonyl group, a carbamoyl group, an alkoxy-carbonyl group, a sulfo group (including the salts thereof), a carboxyl group (including the salts thereof), a hydroxyl group (or the salts thereof), a phosphono group (or the salts thereof), or quaternary ammonium and of these substituents, a hydrogen atom, a halogen atom, an alkyl group, a sulfo group (including the salts thereof), a carboxyl group (including the salts thereof), and a hydroxyl group (or the salts thereof) are preferred, and a hydrogen atom, a sulfo group (including the salts thereof), and a carboxyl group (including the salts thereof) are further preferred, in particular it is preferred that at least one of X₁, X₂, X₃, X₄, X₅, x₆ and X₇ represents a sulfo group (including the salts thereof) or a carboxyl group (including the salts thereof).

In formula (L-3), W has the same meaning as W in formula (L-2), and the preferred examples are also the same.

In formula (L-3), X has the same meaning as X in formula (L-2), and the preferred examples are also the same.

In formula (L-3), T₁ and T₂ each has the same meaning as T₁ and T₂ in formula (L-2), and the preferred examples are also the same.

In formula (L-3), R₄₁ and R₄₂ each has the same meaning as R₄₁ and R₄₂ in formula (L-2), and the preferred examples are also the same.

In formula (L-3), V₁ has the same meaning as V₁ in formula (L-2), and the preferred examples are also the same.

The especially preferred combinations as the compounds represented by formula (L-3) are combinations containing the following (a) to (f).

-   (a) X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each represents a hydrogen atom, a     halogen atom, an alkyl group, an aryl group, a heterocyclic group, a     cyano group, an alkoxyl group, an amido group, a ureido group, an     alkylsulfonylamino group, an arylsulfonylamino group, a sulfamoyl     group, an alkylsulfonyl group, an arylsulfonyl group, a carbamoyl     group, an alkoxycarbonyl group, a sulfo group (including the salts     thereof), a carboxyl group (including the salts thereof), a hydroxyl     group (or the salts thereof), a phosphono group (or the salts     thereof), or quaternary ammonium, and of these substituents, a     hydrogen atom, a halogen atom, an alkyl group, a sulfo group     (including the salts thereof), a carboxyl group (including the salts     thereof), and a hydroxyl group (Or the salts thereof) are preferred,     and a hydrogen atom, a sulfo group (including the salts thereof),     and a carboxyl group (including the salts thereof) are further     preferred, in particular it is preferred that at least one of X₁,     X₂, X₃, X₄, X₅, X₆ and X₇ represents a sulfo group (including the     salts thereof) or a carboxyl group (including the salts thereof). -   (b) W preferably represents a substituted phenyl group, a     substituted or unsubstituted naphthyl group, or a substituted or     unsubstituted heterocyclic group (e.g., a pyrrole ring, a thiophene     ring, an imidazole ring, a thiazole ring, a benzothiazole ring, a     pyridine ring, or a pyridazine ring), and especially preferably a     substituted phenyl group (in particular, a phenyl group substituted     at the para-position), a substituted or unsubstituted β-naphthyl     group, a pyridine ring, or a thiazole ring. -   (c) X represents an N atom or ═CW₁—, and W₁ represents an electron     attracting group having a Hammett's substitution constant op value     of 0.20 or more. More specifically, W₁ preferably represents an acyl     group having from 2 to 20 carbon atoms, an alkyloxycarbonyl group     having from 2 to 20 carbon atoms, a nitro group, a cyano group, an     alkylsulfonyl group having from 1 to 20 carbon atoms, an     arylsulfonyl group having from 6 to 20 carbon atoms, a carbamoyl     group having from 1 to 20 carbon atoms, or a halogenated alkyl group     having from 1 to 20 carbon atoms, especially preferably a cyano     group, an alkylsulfonyl group having from 1 to 20 carbon atoms, or     an arylsulfonyl group having from 6 to 20 carbon atoms, and most     preferably a cyano group. -   (d) T₁ and T₂ each represents ═CR₄₃— or —C₄₄═, or either one     represents a nitrogen atom and the other represents ═CR₄₃— or —C₄₄═,     but the case where T₁ and T₂ each represents ═CR₄₃— or —CR₄₄═ is     preferred for the reason of capable of exhibiting more excellent     performance. -   (e) R₄, and R₄₂ each preferably represents a hydrogen atom, an alkyl     group, an aryl group, a heterocyclic group, an acyl group, an     alkylsulfonyl group, or an arylsulfonyl group, more preferably a     hydrogen atom, an alkyl group, an aryl group, or a heterocyclic     group, especially preferably a hydrogen atom, an aryl group having a     substituent, or a heterocyclic group having a substituent, and most     preferably a hydrogen atom or an aryl group having a substituent.     However, R₄₁ and R₄₂ do not represent a hydrogen atom at the same     time, and R₄₃ and R₄₁, or R₄₁ and R₄₂ may be bonded to each other to     form a 5- or 6-membered ring. -   (f) V₁ represents a hydrogen atom, a halogen atom, an alkyl group, a     hydroxyl group, an alkoxyl group, an aryloxy group, a heterocyclic     oxy group, a silyloxy group, an acyloxy group, an amino group     (including an alkylamino group, an arylamino group, and a     heterocyclic amino group), or an acylamino group, preferably a     hydrogen atom, an amino group (including an alkylamino group, an     arylamino group, and a heterocyclic amino group), or an acylamino     group, especially preferably an amino group having a substituent,     and most preferably an amino group substituted with an aryl group     having an ionic hydrophilic group as the substituent (e.g., a     substituted anilino group, etc.).

Regarding combination of the preferred substituents of the dyestuff represented by formula (L-3), a compound wherein at least one of various substituents is the above preferred group is preferred, a compound wherein more substituents of various substituents are the above preferred groups is more preferred, and a compound wherein all the substituents are the preferred groups is most preferred.

The compound represented by formula (L-3) is preferably a compound represented by the following formula (L-4) and/or the following formula (L-5).

In formula (L-4), R₄₃ has the same meaning as R₄₃ in formula (L-1); R₄₄ has the same meaning as R₄₄ in formula (L-1); R₄₅ and R₄₆ each has the same meaning as R₄₁ and R₄₂ in formula (L-1); and R₄₁ and R₄₂ each has the same meaning as R₄₁ and R₄₂ in formula (L-1).

W has the same meaning as W in formula (L-3); and X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each has the same meaning as. X₁, X₂, X₃, X₄, X₅, X₆ and X₇ in formula (L-3).

In formula (L-5), R₄₃ has the same meaning as R₄₃ in formula (L-1); R₄₄ has the same meaning as R₄₄ in formula (L-1); R₄₅ and R₄₆ each has the same meaning as R₄₁ and R₄₂ in formula (L-3); R₄₁ and R₄₂ each has the same meaning as R₄₁ and R₄₂ in formula (L-3); W has the same meaning as W in formula (L-3); W₁₁ has the same meaning as W₁ in formula (L-2); and X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each has the same meaning as X₁, X₂, X₃, X₄, X₅, X₆ and X₇ in formula (L-3).

Formula (L-4) is described in detail below.

Tn formula (L-4), X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each has the same meaning as X₁, X₂, X₃, X₄, X₅, X₆ and X₇ in formula (L3), and the preferred examples are also the same.

In formula (L-4), W has the same meaning as W in formula (L-3), and the preferred examples are also the same.

In formula (LA4), R₄₁ and R₄₂ each has the same meaning as R₄₁ and R₄₂ in formula (L-3), and the preferred examples are also the same.

In formula (L-4), R₄₃ and R₄₄ each has the same meaning as R₄₃ and R₄₄ in formula (L-1), and the preferred examples are also the same.

In formula (L-1), R₄₅ and R₄₆ each has the same meaning as R₄₁ and R₄₂ in formula (L-3), and the preferred examples are also the same.

The especially preferred combinations as the compounds represented by formula (L-4) are combinations containing the following (a) to (e).

-   (a) X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each represents a hydrogen atom, a     halogen atom, an alkyl group, an aryl group, a heterocyclic group, a     cyano group, an alkoxyl group, an amido group, a ureido group, an     alkylsulfonylamino group, an arylsulfonylamino group, a sulfamoyl     group, an alkylsulfonyl group, an arylsulfonyl group, a carbamoyl     group, an alkoxycarbonyl group, a sulfo group (including the salts     thereof), a carboxyl group (including the salts thereof), a hydroxyl     group (or the salts thereof), a phosphono group (or the salts     thereof), or quaternary ammonium, and of these substituents, a     hydrogen atom, a halogen atom, an alkyl group, a sulfo group     (including the salts thereof), a carboxyl group (including the salts     thereof), and a hydroxyl group (or the salts thereof) are preferred,     and a hydrogen atom, a sulfo group (including the salts thereof),     and a carboxyl group (including the salts thereof) are further     preferred, in particular it is preferred that at least one of X₁,     X₂, X₃, X₄, X₅, X₆ and X₇ represents a sulfo group (including the     salts thereof) or a carboxyl group (including the salts thereof). -   (b) W preferably represents a substituted phenyl group, a     substituted or unsubstituted naphthyl group, or a substituted or     unsubstituted heterocyclic group (e.g., a pyrrole ring, a thiophene     ring, an imidazole ring, a thiazole ring, a benzothiazole ring, a     pyridine ring, or a pyridazine ring), and especially preferably a     substituted phenyl group (in particular, a phenyl group substituted     at the para-position), a substituted or unsubstituted β-naphthyl     group, a pyridine ring, or a thiazole ring. -   (c) R₄₁ and R₄₂ each preferably represents a hydrogen atom, an alkyl     group, an aryl group, a heterocyclic group, an acyl group, an     alkylsulfonyl group, or an arylsulfonyl group, more preferably a     hydrogen atom, an alkyl group, an aryl group, or a heterocyclic     group, especially preferably a hydrogen atom, an aryl group having a     substituent, or a heterocyclic group having a substituent, and most     preferably a hydrogen atom or an aryl group having a substituent.     However, R₄₁ and R₄₂ do not represent a hydrogen atom at the same     time, and R₄₃ and R₄₁, or R₄₁ and R42 may be bonded to each other to     form a 5- or 6-membered ring. -   (d) R₄₃ and R₄₄ each preferably represents a hydrogen atom, a     halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an     aralkyl group, an aryl group, a heterocyclic group, a cyano group, a     carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an     aryloxycarbonyl group, a heterocyclic oxycarbonyl group, a hydroxyl     group, an amino group (including an alkylamino group, an arylamino     group, and a heterocyclic amino group), an acylamino group, a ureido     group, a sulfamoylamino group, an alkoxycarbonylamino group, an     aryloxycarbonylamino group, an alkylsulfonylamino group, an     arylsulfonylamino group, or a heterocyclic sulfonylamino group, and     each group may further be substituted.

R₄₃ more preferably represents a hydrogen atom, a halogen atom, an aryl group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a heterocyclic oxycarbonyl group, still more preferably a cyano group, a carboxyl group, a carbamoyl group, or an alkoxycarbonyl group, and especially preferably a cyano group.

R₄₄ more preferably represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a heterocyclic group, a hydroxyl group, an amino group (including an alkylamino group, an arylamino group, and a heterocyclic amino group), an acylamino group, a ureido group, a sulfamoylamino group, an alkoxy-carbonylamino group, an aryloxycarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, or a heterocyclic sulfonylamino group, still more preferably a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, or an aryl group, and most preferably a methyl group.

-   (c) R₄₅ and R₄₆ each preferably represents a hydrogen atom, an alkyl     group, an aryl group, a heterocyclic group, an acyl group, an     alkylsulfonyl group, or an arylsulfonyl group, and more preferably a     hydrogen atom, an alkyl group, an aryl group, or a heterocyclic     group, especially preferably a hydrogen atom, an aryl group having a     substituent, or a heterocyclic group having a substituent, and most     preferably a hydrogen atom or an aryl group having a substituent.     However, R₄₅ and R₄₆ do not represent a hydrogen atom at the same     time, and R₄₅ and R₄₆ may be bonded to each other to form a 5- or     6-membered ring.

Regarding combination of the preferred substituents of the dyestuff represented by formula (L-4), a compound wherein at least one of various substituents is the above preferred group is preferred, a compound wherein more substituents of various substituents are the above preferred groups is more preferred, and a compound wherein all the substituents are the preferred groups is most preferred.

Formula (L-5) is described in detail below.

In formula (L-5), X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each has the same meaning as X₁, X₂, X₃, X₄, X₅, X₆ and X₇ in formula (L-3), and the preferred examples are also the same.

In formula (L-5), W has the same meaning as W in formula (L-3), and the preferred examples are also the same.

In formula (L-5), W₁₁ has the same meaning as W₁ in formula (L-2), and the preferred examples are also the same.

In formula (L-5), R₄₁ and R₄₂ each has the same meaning as R₄₁ and R₄₂ in formula (L-3), and the preferred examples arc also the same.

In formula (LP5), R₄₃ and R₄₄ each has the same meaning as R₄₃ and R₄₄ in formula (L-1), and the preferred examples are also the same.

In formula (L-5), R₄₅ and R₄₆ each has the same meaning as R₄₁ and R₄₂ in formula (L-3), and the preferred examples are also the same.

The especially preferred combinations as the compounds represented by formula (L-5) are combinations containing the following (a) to (f).

-   (a) X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each represents a hydrogen atom, a     halogen atom, an alkyl group, an aryl group, a heterocyclic group, a     cyano group, an alkoxyl group, an amido group, a ureido group, an     alkylsulfonylamino group, an arylsulfonylamino group, a sulfamoyl     group, an alkylsulfonyl group, an arylsulfonyl group, a carbamoyl     group, an alkoxycarbonyl group, a sulfo group (including the salts     thereof), a carboxyl group (including the salts thereof), a hydroxyl     group (or the salts thereof), a phosphono group (or the salts     thereof), or quaternary ammonium, and of these substituents, a     hydrogen atom, a halogen atom, an alkyl group, a sulfo group     (including the salts thereof), a carboxyl group (including the salts     thereof), and a hydroxyl group (or the salts thereof) are preferred,     and a hydrogen atom, a sulfo group (including the salts thereof),     and a carboxyl group (including the salts thereof) are firer     preferred, ill particular it is preferred that at least one of X₁,     X₂, X₃, X₄, X₅, X₆ and X₇ represents a sulfo group (including the     salts thereof) or a carboxyl group (including the salts thereof). -   (b) W preferably represents a substituted phenyl group, a     substituted or unsubstituted naphthyl group, or a substituted or     unsubstituted heterocyclic group (e.g., a pyrrole ring, a thiophene     ring, an imidazole ring, a thiazole ring, a benzothiazole ring, a     pyridine ring, or a pyridazine ring), and especially preferably a     substituted phenyl group (in particular, a phenyl group substituted     at the para-position), a substituted or unsubstituted -naphthyl     group, a pyridine ring, or a thiazole ring. -   (c) W₁₁ preferably represents an electron attracting group having a     Hammett's substitution constant op value of 0.20 or more. An     electron attracting group having a σp value of 0.30 or more is     preferred, 0.45 or more is more preferred, and 0.60 or more is     especially preferred, but it is desired that the σp value does not     exceed 1.0. More specifically, W₁₁ preferably represents an acyl     group having from 2 to 20 carbon atoms, an alkyloxycarbonyl group     having from 2 to 20 carbon atoms, a nitro group, a cyano group, an     alkylsulfonyl group having from 1 to 20 carbon atoms, an     arylsulfonyl group having from 6 to 20 carbon atoms, a carbamoyl     group having from 1 to 20 carbon atoms, or a halogenated alkyl group     having from 1 to 20 carbon atoms, especially preferably represents a     cyano group, an alkyl-sulfonyl group having from 1 to 20 carbon     atoms, or an arylsulfonyl group having from 6 to 20 carbon atoms,     and most preferably a cyano group. -   (d) R₄₁ and R₄₂ each preferably represents a hydrogen atom, an alkyl     group, an aryl group, a heterocyclic group, an acyl group, an     alkylsulfonyl group, or an arylsulfonyl group, more preferably a     hydrogen atom, an alkyl group, an aryl group, or a heterocyclic     group, especially preferably a hydrogen atom, an aryl group having a     substituent, or a heterocyclic group having a substituent, and most     preferably a hydrogen atom or an aryl group having a substituent.     However, R₄₁ and R₄₂ do not represent a hydrogen atom at the same     time, and R₄₃ and R₄₁, or R₄, and R₄₂ may be bonded to each other to     form a 5- or 6-membered ring. -   (e) R₄₃ and R₄₄ each preferably represents a hydrogen atom, a     halogen atom, an alkyl group, an alkenyl group, an alkyl group, an     aralkyl group, an aryl group, a heterocyclic group, a cyano group, a     carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an     aryloxycarbonyl group, a heterocyclic oxycarbonyl group, a hydroxyl     group, an amino group (including an alkylamino group, an arylamino     group, and a heterocyclic amino group), an acylamino group, a ureido     group, a sulfamoylamino group, an alkoxycarbonylamino group, an     aryloxycarbonylamino group, an alkylsulfonylamino group, an     arylsulfonylamino group, or a heterocyclic sulfonylamino group, and     each group may further be substituted.

R₄₃ more preferably represents a hydrogen atom, a halogen atom, an aryl group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a heterocyclic oxycarbonyl group, still more preferably a cyano group, a carboxyl group, a carbamoyl group, or an alkoxycarbonyl group, and especially preferably a cyano group.

R₄₄ more preferably represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a heterocyclic group, a hydroxyl group, an amino group (including an alkylamino group, an arylamino group, and a heterocyclic amino group), an acylamino group, a ureido group, a sulfamoylamino group, an alkoxy-carbonylamino group, an aryloxycarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, or a heterocyclic sulfonyl amino group, still more preferably a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, or an aryl group, and most preferably a methyl group.

-   (f) R₄₅ and R₄₆ each preferably represents a hydrogen atom, an alkyl     group, an aryl group, a heterocyclic group, an acyl group, an     alkylsulfonyl group, or an arylsulfonyl group, and more preferably a     hydrogen atom, an alkyl group, an aryl group, or a heterocyclic     group, especially preferably a hydrogen atom, an aryl group having a     substituent, or a heterocyclic group having a substituent, and most     preferably a hydrogen atom or an aryl group having a substituent     However, R₄₅ and R₄₆ do not represent a hydrogen atom at the same     time, and R₄₅ and R₄₆ may be bonded to each other to form a 5- or     6-membered ring.

Regarding combination of the preferred substituents of the dyestuff represented by formula (L-5), a compound wherein at least one of various substituents is the above preferred group is preferred, a compound wherein more substituents of various substituents are the above preferred groups is more preferred, and a compound wherein all the substituents arc the preferred groups is most preferred.

The compound represented by formula (L-4) and/or (L-5) is preferably a compound represented by the following formula (L-4-1) and/or (L-5-1) for the reason of capable of exhibiting more excellent performance.

In formula (L-4-1), R₁₁ and R₁₂ each represents an ionic hydrophilic group, especially preferably a sulfo group (including the salts thereof), or a carboxyl group (including the salts thereof), and a sulfo group is preferred above all; m and n each represents an integer of from 1 to 3, especially preferably an integer of 1 or 2, and m and n each most preferably represents 1; W has the same meaning as W in formula (L-4), and the preferred examples are also the same; and X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each has the same meaning as X₁, X₂, X₃, X₄, X₅, X₆ and X₇ in formula (L-4), and the preferred examples are also the same.

In formula (L-5-1), R₁₁ and R₁₂ each represents an ionic hydrophilic group, especially preferably a sulfo group (including the salts thereof), or a carboxyl group (including the salts thereof), and a sulfo group is preferred above all; m and n each represents an integer of from 1 to 3, especially preferably an integer of 1 or 2, and m and n each most preferably represents 1; W has the same meaning as W in formula (L-5), and the preferred examples are also the same; W₁₁ has the same meaning as W₁₁ in formula (L-5), and the preferred examples are also the same; and X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each has the same meaning as X₁, X₂, X₃, X₄, X₅, X₆ and X₇ in formula (L-5), and the preferred examples are also the same.

The specific examples of the azo dyes represented by formula (L-1) are shown below, but the invention is not limited thereto. The carboxyl group, phosphono group and sulfo group in the following specific examples may be in the state of salts, and the examples of counter ions for forming the salt include an ammonium ion, an alkali metal ion (e.g., a lithium ion, a sodium ion, a potassium ion), and an organic cation (e.g., a tetramethylammonium ion, a tetramethylguanidinium ion, a tetramethylphosphonium ion). Of these counter ions, the cases of an ammonium ion, an organic cation and a lithium ion are preferred, and a lithium ion is most preferred

It is preferred for the ink composition in the invention to contain the counter ion. A—N═N—B—N═N—C A B C (a-1)

(a-2)

(a-3)

(a-4)

(a-5)

(a-6)

(b-1)

(b-2)

(b-3)

(b-4)

(b-5)

(b-6)

(b-7)

(c-1)

(c-2)

(c-3)

(c-4)

(c-5)

(d-1)

(d-2)

(d-3)

(d-4)

(d-5)

(d-6)

(e-1)

(e-2)

(f-1)

(f-2)

(f-3)

(f-4)

(g-1)

(g-2)

(g-3)

(g-4)

(g-5)

(g-6)

(h-1)

(h-2)

(h-3)

(h-4)

(h-5)

(h-6)

(i-1)

(i-2)

(i-3)

(i-4)

(i-5)

(i-6)

(j-1)

(j-1)

(j-1)

(j-1)

(j-1)

(j-1)

(k-1)

(k-2)

(k-3)

(k-4)

(k-5)

(k-6)

(l-1)

(l-2)

(l-3)

(l-4)

(l-5)

(l-6)

(m-1)

(m-2)

(m-3)

(m-4)

(m-5)

(m-6)

(n-1)

(n-2)

(n-3)

(n-4)

(n-5)

(n-6)

(o-1)

(o-2)

(o-3)

(o-4)

(o-5)

(o-6)

In the invention, in addition to at least one compound represented by formula (L-1), a salt thereof, or a compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups, at least other water-soluble long wave dye L having a different structure is used in combination

By using a compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups, an image excellent in image fastness and free from blotting in preservation under a high humidity condition can be obtained.

The more the number of azo groups of a compound, the higher is the molecular weight, so that the blotting of image can be restrained in preservation under a high humidity condition, but the solubility in ink is liable to lower, and there is a case where the preservation stability of ink becomes a problem. To reconcile these points, the number of azo groups is preferably from 3 to 5.

It is preferred that a compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups has a hydrophilic group.

The examples of the hydrophilic groups include a sulfo group, a carboxyl group, a phosphono group, an amino group, a nitro group, and a quaternary ammonium group. As the hydrophilic groups, a carboxyl group, a phosphono group, an amino group, a nitro group, and a sulfo group are preferred, a carboxyl group and a sulfo group are especially preferred, and a sulfo group is most preferred from the viewpoint of increasing solubility in an aqueous solvent.

The hydrophilic group may be in the form of a salt. In the examples of ions having counter charge to hydrophilic groups and forming salt (ion pair) (hereinafter referred to as a counter salt or a counter ion), ammonium, an alkali metal (e.g., lithium, sodium, potassium), an organic cation (tetramethylammonium, tetramethylguanidinium, tetramethyl-phosphonium) and the like are included. As the counter ions, each ion of ammonium, lithium, sodium and potassium are preferred, a sodium ion and a lithium ion are more preferred, and a lithium ion is most preferred.

A compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups is preferably a compound selected from the compounds represented by formula (L-6), (L-6a), (L-7) or (L-8).

In addition to at least one compound represented by formula (L-1), a salt thereof, or a compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups, it is preferred to use at least one compound different in structure represented by any of formulae (L-1) to (L-5) in combination, or a compound represented by any of formulae (L-1) to (L-5), and a compound represented by any of formulae (L-6) to (L-8) in combination. Water-soluble long wave dyes L usable in combination are not especially restricted so long as the above conditions of water-soluble long wave dye L are satisfied.

By the use of water-soluble long wave dye L different in structure in combination with the compound represented by formula (L-1), a black image having high density can be obtained and bronze glossiness at a high density part can be restrained as compared with the case where the compound represented by formula (L-1) is used alone. The cause of the effect is not clearly known, but it is presumed that by the use of the compound represented by formula (L-1), which is a dye having an associating property, and water-soluble long wave dye L different in structure in combination, the association of the compound represented by formula (L-1) is loosened in a degree of not impairing image fastness.

Not to impair image fastness, water-soluble long wave dye L to be used in combination is preferably fast to light and ozone gas. Further, to lessen the change in hue at the time of deterioration of images by light and ozone, it is preferred that the value of discoloring speed constant of water-soluble long wave dye L to be used in combination approximates to that of the discoloring speed constant of the compound of formula (L-1). Specifically, the ratio of both values is more preferably in the range of from 0.5 to 2.0, but it is not restrictive thereto. The discoloring speed constant can be found with each of light fastness and ozone-proofness according to the method disclosed in JP-A-2004-107638, paragraphs [0011] and [0012].

The blending ratio of the compound represented by formula (L-1) and water-soluble long wave dye L to be used in combination, [addition amount of formula (L-1) (g)]/[addition amount of water-soluble long wave dye L used in combination (g)] is preferably from 0.3 to 100, more preferably from 0.6 to 20, and still more preferably from 1.0 to 10. When the blending ratio is less than 0.3, the addition amount of formula (L-1) is not sufficient and there is a possibility that image fastness is inferior, while when it is greater than 100, the addition amount of the dye to be used in combination is deficient, so that the effects of image density and restraint of bronze glossiness arc not sometimes satisfactory.

In the invention, it is possible to use two or more compounds represented by formula (L-1) in combination. In that case, it is preferred to define a dye having the strongest associating property as the compound represented by formula (L-1) and the other dyes as water-soluble long wave dyes L to be used in combination in the method of judging the associating property from the visible absorption spectra (described in paragraph [0035]) so as to be in the above blending ratio.

From the viewpoints of being fast to light and ozone gas and the value of discoloring speed constant approximates to that of the compound of formula (L-1), water-soluble long wave dye L to be used in combination is preferably selected from formulae (L-4), (L-5), (L-6), (L-6a), (L-7) and (L-8).

Formulae (L-4) and (L-5) and the preferred examples arc described above. The compounds represented by formulae (L-4) and (L-5) can be preferably used as the compound of formula (L-1), and as water-soluble long wave dye L to be used in combination with the compound represented by formula (L-4), the compound of formula (L-4) may be used (this is also applied to the compound of formula (L-5)). As the dye to be used in combination at this time, a dye having a smaller degree of an associating property is preferred.

When the compounds of formulae (L-4) and (L-5) are added as water-soluble long wave dyes L to be used in combination, the difference in structure between the compound of formula (L-1) and water-soluble long wave dyes L is not especially restricted so long as the formulae are satisfied, but it is preferred that the site of B in formula (L-1) differs. As an example, the combination of the compound of formula (L-4) and the compound of formula (L-5) is exemplified, but the invention is not restricted thereto. Further, when two or more kinds of the compounds of formula (L-4) are used in combination, it is preferred that the structures of the site of W in formula (L-4) differ. When two or more kinds of the compounds of formula (L-5) are used in combination, it is also preferred that the compounds differ in the structures of the site of W similarly to the case of formula (L-4).

In formula (L-6), R₁₁ and R₁₂ each represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a sulfamoyl group that may be substituted with an alkyl group or a phenyl group; a phosphoric acid group; a nitro group; an acyl group; a ureido group; an alkyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group or an alkoxyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms or an acylamino group that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group, or a carboxyl group; E represents a phenyl group or a naphthyl group, which may be substituted with a halogen atom; a cyano group; a carboxyl group; a sulfo group; a sulfamoyl group that may be substituted with an alkyl group or a phenyl group; a phosphoric acid group; a nitro group; an acyl group; a ureido group; an alkyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group or an alkoxyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms or an acylamino group that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group or a carboxyl group; and n₁ represents 0 or 1.

The compound represented by formula (L-6) is preferably a compound represented by the following formula (L-10).

In formula (L-10), R₁₃, R₁₄ and R₁₅ each represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a sulfamoyl group that may be substituted with an alkyl group having from 1 to 4 carbon atoms or a phenyl group; a phosphoric acid group; a nitro group; an acyl group; a ureido group; an alkyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group or an alkoxyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms or an acylamino group that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group, or a carboxyl group; and at least one of R₁₃, R₁₄ and R₁₅ is a sulfo group or a carboxyl group; and n₁ is 0 or 1.

The specific examples of preferred compounds represented by formula (L-6) and the salts thereof are shown below, but the invention is not restricted thereto. The following specific examples are shown in a free acid structure, but of course the compounds may be used in the form of an arbitrary salt.

The compound represented by formula (L-6) and the salts thereof arc disclosed in detail in JP-A-2005-220211, and the compounds shown in the same patent can be preferably used.

In formula (L-6a), A represents the following formula (L-6a-1), and the substitution position of A is the m- or p-position to the azo group; R¹ and R² each represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a sulfamoyl group; an N-alkylaminosulfonyl group; an N-phenylaminosulfonyl group; a phospho group; a nitro group; an acyl group; a ureido group; an alkyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group or an alkoxyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group, or a carboxyl group; or an acylamino group that may be substituted with an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group, or a carboxyl group; R³ and R⁴ each represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a nitro group; an alkyl group having from 1 to 4 carbon atoms; a hydroxyl group; or an alkoxyl group having from 1 to 4 carbon atoms that may be substituted with an alkoxyl group having from 1 to 4 carbon atoms or a sulfo group; and n represents 0 or 1.

In formula (L-6a-1), R⁵ represents a cyano group; a carboxyl group; an alkyl group having from 1 to 4 carbon atoms; an alkoxycarbonyl gruop having from 1 to 4 carbon atoms, or a phenyl group; R⁶, R⁷ and R⁸ each represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a nitro group; an alkyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms that may be substitutted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, or a sulfo group; or an acylamino group that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, or a sulfo group.

The specific examples of preferred compounds represented by formula (L-6a) and the salts thereof are shown below, but the invention is not restricted thereto. The following specific examples (Compound Nos. 1 to 27) are shown in a free acid structure, but of course the compounds may be used in the form of an arbitrary salt. Cpd. No. Structural Formula 1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

The compound represented by formula (1-6a) and the salts thereof are disclosed in detail in JP-A-2005-097912, and the compounds shown in the same patent can be preferably used.

In formula (L-7), G and J each represents a phenyl group or a naphthyl group that may be substituted, or a 5- or 6-membered aromatic heterocyclic group bonding to the azo group via a carbon atom, and each of G and J contains at least one or more carboxyl group(s) or sulfo group(s); one of X and Y represents a hydroxyl group, and the other represents an amino group; and t₂, m₂ and n₂ each represents 1 or 2.

She compound represented by formula (L-7) is preferably a compound represented by the following formula (L-11).

In formula (L-11), G and J each represents a phenyl group or a naphthyl group that may be substituted, or a 5- or 6-membered aromatic heterocyclic group bonding to the azo group via a carbon atom, and each of G and J contains at least one or more carboxyl group(s) or sulfo group(s); a and b each represents a single bond, the bonding position of bond a is the 2- or 3-position, and the bonding position of bond b is the 6- or 7-position; one of X and Y represents a hydroxyl group, and the other represents an amino group; and l₃, m₃ and n₃ each represents 0 or 1.

In formula (L-11), G and J each preferably represents a phenyl group or a naphthyl group that may be substituted with a substituent containing at least one or more carboxyl group(s) and/or sulfo group(s). The examples of the substituents substituted on G and J include a halogen atom; a hydroxyl group; an amino group; a carboxyl group; a sulfo group; a nitro group; an alkyl group; an alkoxyl group; an acyl group; a phenyl group; a ureido group; an alkyl group substituted with a hydroxyl group, an alkoxyl group, a sulfo group, or a carboxyl group; an alkoxyl group substitutted with a hydroxyl group, an alkoxyl group, a sulfo group, or a carboxyl group; a phenyl group that may be substituted with a carboxyl group or a sulfo group; and an amino group substituted with an alkyl group or an acyl group.

In formula (L11), it is preferred that G and J each has a sulfo group at the o-position to the azo group, and represents a phenyl group that may be substituted with a nitro group, an alkoxyl group, or a sulfo group

The specific examples of preferred compounds represented by formula (L-7) and the salts thereof are shown below, but the invention is not restricted thereto. The following specific examples are shown in a free acid structure, but of course the compounds may be used in the form of an arbitrary salt.

The compound represented by formula (L-7) and the salts thereof are disclosed in detail in JP-A-2004-285351, and the compounds shown in the same patent can be preferably used.

In formula (L-8), R₂₁ represents a phenyl group having a substituent, or a naphthyl group having a substituent; R₂₂ represents a phenylene group having a substituent, or a naphthylene group having a substituent; R₂₃ represents a 5- to 7-membered heterocyclic group having at least one double bond and a substituent; and the substituents in R₂₁, R₂₂ and R₂₃ are each selected from the group consisting of OH, SO₃H, PO₃H₂, CO₂H, NO₂, NH₂, an alkyl group having from 1 to 4 carbon atoms, an alkyl group having a substituent, an alkoxyl group having from 1 to 4 carbon atoms, an alkoxyl group having a substituent, an amino group, an amino group having a substituent, and a phenyl group having a substituent.

The compound represented by formula (L-8) is preferably a compound represented by the following formula (L-9) and the salts thereof

In formula (L-9), R₃₁ to R₃₉ each represents a group selected from the group consisting of H, OH, SO₃H, PO₃H₂, CO₂H, NO₂, and NH₂.

The specific examples of preferred compounds represented by formula (L-8) or (L-9) and the salts thereof are shown below, but the invention is not restricted thereto. The following specific examples are shown in a free acid structure, but of course the compounds may be used in the form of an arbitrary salt.

The compounds represented by formula (L-8) or (L-9) and the salts thereof are disclosed in detail in WO 03/106572 and JP-A-2005-2271, and the compounds shown in the same patents can be preferably used.

In the invention, the later-described water-soluble short wave dye S can be used as a color correction dye.

Water-Soluble Short W Dye S:

Water-soluble short wave dye S that can be used in the invention has the maximum of an absorption spectrum (the absorption maximum: λmax) in an aqueous solvent of from 400 to 540 nm. The half value width of the absorption spectra is preferably from 90 to 200 nm, and a dye capable of achieving broad absorption is preferred.

The absorption spectrum of water-soluble short wave dye S is an absorption spectrum measured with a single compound. That is, when an absorption spectrum in an aqueous solvent is measured, water-soluble short wave dye S in the invention means to show the physical properties such as the desired absorption maximum and half value width not by combining a plurality of compounds but to show these physical properties by a single compound. Incidentally, it is apparent in the invention that as water-soluble short wave dyes S (hereinafter also referred to as “short wave dye S”), compounds having structures different from each other may be used in combination so long as they satisfy the absorption spectra.

Having such absorption characteristics, short wave dye S can absorb lights in a broad range from blue to green that is liable to be insufficient with the absorption spectra of water-soluble long wave dye L such as a dis-azo dye or a tris-azo dye, and has preferred absorption characteristics as a color correction dye.

The absorption maximum of short wave dye S is preferably from 400 to 540 nm, and especially preferably from 460 to 500 nm.

The half value width at the absorption maximum of short wave dye S is preferably from 100 to 180 nm, and especially preferably from 110 to 160 nm.

It is preferred for short wave dye S in the invention not to have a dissociable phenolic hydroxyl group that is present in ordinary dyestuffs, which structure ensures preferred properties, for example, variation in color tone dependent upon the image-receiving material used is little, and reactivity with oxidizing gas, e.g., ozone in the air, is low and excellent in an anti gas property.

Here, “a dissociable phenolic hydroxyl group” means a dissociable hydroxyl group that is substituted with an aryl group. The aryl group may be substituted with other substituent.

It is preferred for short wave dye S in the invention to have from 2 to 6 azo groups in one molecule, which structure enhances a color developing property, and provides images having good fixing ability due to the broadened plane of dyestuff.

Further, the number of azo groups is more preferably from 4 to 6 in one molecule in respects of a color developing property and fixing ability.

Short wave dyes S are not especially restricted so long as they have the physical properties defined in the invention and capable of dissolving the foregoing problem, and a polyazo dye represented by the following formula can be exemplified: (D)_(n)-Y

In the formula, D represents a dye residue of chromophore consisting of from 1 to 3 azo groups conjugated to each other, and from 3 to 4 aromatic rings having 20 or more π electrons in total, and n is 1 or 2. When n is 1, Y represents a hydrogen atom, and when n is 2, Y represents a divalent linking group. The aromatic rings composing chromophore may be heterocyclic rings or hydrocarbon rings, but preferably hydrocarbon rings. In the case where the aromatic rings composing chromophore form a condensed ring, the number of π electrons on the aromatic rings is the number of π electrons of the condensed ring as a whole, e.g., the number of π electrons of a naphthalene ring is 10. The divalent linking group represented by Y is an alkylene group, an arylene group, a heterocyclic residue, —CO—, —SO_(n)— (where n is 0, 1 or 2), —NR— (where R represents a hydrogen atom, an alkyl group, or an aryl group), —O—, or a divalent linking group combining these linking groups, and these groups may further have a substituent, e.g., an alkyl group, an aryl group, an alkoxyl group, an amino group, an acyl group, an acylamino group, a halogen atom, a hydroxyl group, a carboxyl group, a sulfamoyl group, a carbamoyl group, a sulfonamido group, etc. As the especially preferred examples of linking groups, —NH—CO—NH—, —NH—CS—NH—, and a group represented by the following formula can be exemplified.

In the specification of the invention, an alkyl group means a straight chain, branched, cyclic (including monocyclic, polycyclic, and a bridged form and spiro in the case of polycyclic), or monovalent saturated hydrocarbon group obtained by combining these alkyl groups, and includes a cycloalkyl group, a cycloalkylalkyl group, etc., and further includes a substituted alkyl group in the case where an alkyl group may be substituted.

In the specification of the invention, an alkenyl group means a straight chain, branched, cyclic (including monocyclic, polycyclic, and a bridged form and spiro in the case of polycyclic), or monovalent unsaturated hydrocarbon group obtained by combining these alkenyl groups having one or more carbon-carbon double bond exclusive of aromatic groups, and further includes a substituted alkenyl group in the case where an alkenyl group may be substituted.

In the specification of the invention, for example, a substituted alkyl group means an alkyl group whose hydrogen atom is substituted with a substituent, and the substituent may be one or more, and one or more hydrogen atoms may be substituted. This is also applied to a substituted aryl group.

In the formula, X represents a hydroxyl group, a sulfo group, an alkoxyl group, an aryloxy group, an amino group (including an alkylamino group and an arylamino group), an alkylsulfenyl group, or an arylsulfenyl group, and each group may further have a substituent.

As short wave dye S, for example, commercially available C.I. Direct Red 84, C.I. Direct Brown 106, and C.I. Direct Brown 202 arc useful, and C.I. Direct Red 84 that ran be used for the correction of tone of many black dyes and excellent in a color developing property and fastness is especially useful.

The examples of short wave dyes S preferably used in the invention arc shown below in a free acid structure, but of course the compounds may be used in the form of an arbitrary salt.

As preferred counter cations, an alkali metal (e.g., lithium, sodium, potassium), ammonium, and an organic cation (e.g., pyridinium, tetramethylammonium, guadinium) can be exemplified.

A SB-1

SB-2

SB-3

SB-4

SB-5

SB-6

A X SB-7

—NHC₂H₄OH SB-8

—NHC₂H₄OH SB-9

—NHC₂H₄OH SB-10

—N(C₂H₄OH)₂) SB-11

—N(C₂H₄OH)₂) SB-12

—NHC₂H₄OH

A SB-13

SB-14

SB-15

Of these short wave dyes S, C.I. Direct Red 84 (sodium salt of the Exemplified Compound SB-2), and C.T. Direct Brown 106 (sodium salt of the Exemplified Compound SB-14) are preferred for capable of available as commercial dye, and C.T. Direct Red 84 excellent in a color developing property, fastness and a fixing property is especially useful.

As the examples of the counter salts of C.I. Direct Red 84 and C.I. Direct Brown 106, ammonium, an alkali metal (e.g., lithium, sodium, potassium), and an organic cation (e.g., tetramethylammonium, tetramethylguadinium, tetramethyl-phosphonium) can be exemplified. As the counter salts, ammonium, lithium, sodium, and potassium are preferred, and sodium and lithium are more preferred. Sodium salts are commercially available as above and preferred. It is known that the use of lithium salts as counter salts results in the improvement of the solubility of dyes in water, so that very preferred from the respects of stability and precipitation by aging in the state of ink.

Incidentally, short wave dyes S other than commercially available dyes can be easily synthesized with commercially available materials according to the synthesizing route of C.I. Direct Red 84 or C.I. Direct Brown 106 as described in Color Index, Vol. 4, published by The Society of Dyers and Colourists.

The black ink composition in the invention contains from 0.1 to 4 mass % of short wave dye S, preferably from 0.5 to 3.0 mass %, and especially preferably from 1.0 to 2.5 mass %, but the amount can be arbitrarily changed as desired. (In this specification, mass ratio is equal to weight ratio.)

Other Dyes:

Further, other dyes can also be used in combination in the invention for adjusting the tone and the like of a black ink composition in the range not greatly impairing light fastness and ozone-proofness.

As yellow dyes, aryl or heteryl azo dyes having, e.g., phenols, naphthols, anilines, pyrazolones, pyridones or open chain type active methylene compounds as the coupling component; azomethine dyes having, e.g., open chain type active methylene compounds as the coupling component; methine dyes, such as benzylidene dyes and monomethine oxonol dyes; and quinone dyes, such as naphthoquinone dyes and anthraquinone dyes are exemplified. Besides these kinds of dyes, quinophthalone dyes, nitro-nitroso dyes, acridine dyes and acridinone dyes are exemplified. These dyes may be dyes that present yellow not until after a part of the chromophore has been dissociated, and the counter cations in that case may be inorganic cations, e.g., an alkali metal and ammonium, or may be organic cations, e.g., pyridinium and quaternary ammonium salt, or the counter cations may be polymer cations having these cations as the partial structure.

As magenta dyes, aryl or heteryl azo dyes having, e.g., phenols, naphthols or anilines as the coupling component; azomethine dyes having, e.g., pyrazolones or pyrazolo-triazoles as the coupling component; methine dyes, e.g., arylidene dyes, styryl dyes, merocyanine dyes, and oxonol dyes; carbonium dyes, e.g., diphenylmethane dyes, triphenylmethane dyes, and xanthene dyes; quinone dyes, e.g., naphthoquinone, anthraquinone and anthrapyridone; and condensation polycyclic dyestuffs, e.g., dioxazine dyes are exemplified. These dyes may be dyes that present magenta not until after a part of the chromophore has been dissociated, and the counter cations in that case may be inorganic cations, e.g., alkali metal and ammonium, or may be organic cations, e.g., pyridinium and quaternary ammonium salt, or the counter cations may be polymer cations having these cations as the partial structure.

As cyan dyes, azomethine dyes, e.g., indoaniline dyes and indophenol dyes; polymethine dyes, e.g., cyanine dyes, oxonol dyes and merocyanine dyes; carbonium dyes, e.g., diphenylmethane dyes, triphenylmethane dyes and xanthene dyes; phthalocyanine dyes; anthraquinone dyes; aryl or heteryl azo dyes having, e g., phenols, naphthols or anilines as the coupling component; and indigo thioindigo dyes are exemplified. These dyes may be dyes that present cyan not until after a part of the chromophore has been dissociated, and the counter cations in that case may be inorganic cations, e.g., alkali metal and ammonium, or may be organic cations, e.g., pyridinium and quaternary ammonium salt) or the counter cations may be polymer cations having these cations as the partial structure.

Black dyes, e.g., polyazo dye, can also be used.

Water-soluble dyes, such as direct dyes, acid dyes, food dyes, basic dyes, and reactive dyes can also be used in combination. Preferred dyes of such dyes are listed below, but the invention is not restricted thereto:

-   C.I. Direct Red 2, 4, 9, 11, 23,26, 31, 37, 39, 62, 63, 72, 75, 76,     79, 80, 81, 83, 84, 87, 89, 92, 95, 111, 173, 184, 207, 211, 212,     214, 218, 219, 223, 224, 225, 226, 227, 232, 233, 240, 241, 242,     243, 247, 254 -   C.I. Direct Violet 7, 9, 47, 48, 51, 66, 90, 93, 94, 95, 98, 100,     101 -   C.I. Direct Yellow 4, 8, 9, 11, 12, 27, 28, 29, 33, 35, 39, 41, 44,     50, 53, 58, 59, 68, 86, 87, 93, 95, 96, 98, 100, 106, 108, 109, 110,     120, 130, 132, 142, 144, 157, 161, 163 -   C.I. Direct Blue 1, 10, 15, 22, 25, 55, 67, 68, 71, 76, 77, 78, 80,     84, 86, 87, 90, 98, 106, 108, 109, 151, 156, 158, 159, 160, 168,     189, 192, 193, 194, 199, 200, 201, 202, 203, 207, 211, 213, 214,     218, 225, 229, 236, 237, 244, 248, 249, 251, 252, 264, 270, 280,     288, 289, 290, 291 -   C.I. Direct Black 9, 17, 19, 22, 32, 51, 56, 62, 69, 77, 80, 91, 94,     97, 108, 112, 113, 114, 117, 118, 121, 122, 125, 132, 146, 154, 166,     168, 173, 199 -   C.I. Acid Red 1, 8, 35, 42, 52, 57, 62, 80, 81, 82, 87, 94, 111,     114, 115, 118, 119, 127, 128, 131, 143, 144, 151, 152, 154, 158,     186, 245, 249, 254, 257, 261, 263, 266, 289, 299, 301, 305, 336,     337, 361, 396, 397 -   C.I. Acid Violet 5, 34, 43, 47, 48, 90, 103, 126 -   C.I. Acid Yellow 17, 19, 23, 25, 39, 40, 42, 44, 49, 50, 61, 64, 76,     79, 110, 127, 135, 143, 151, 159, 169, 174, 190, 195, 196, 197, 199,     218, 219, 222, 227 -   C.I. Acid Blue 9, 25, 40, 41, 62, 72, 76, 78, 80, 82, 87, 92, 106,     112, 113, 120, 127:1, 129, 138, 143, 175, 181, 185, 205, 207, 220,     221, 230, 232, 247, 249, 258, 260, 264, 271, 277, 278, 279, 280,     288, 290, 326 -   C.I. Acid Black 7, 24, 29, 48, 52:1., 172 -   C.I. Reactive Red 3, 6, 13, 17, 19, 21, 22, 23, 24, 29, 35, 37, 40,     41, 43, 45, 49, 55, 63, 106, 107, 112, 113, 114, 126, 127, 128, 129,     130, 131, 137, 160, 161, 174, 180 -   C.I. Reactive Violet 1, 3, 4, 5, 6, 7, 8, 9, 16, 17, 22, 23, 24, 26,     27, 33, 34 -   C.I. Reactive Yellow 2, 3, 13, 14, 15, 17, 18, 23, 24, 25, 26, 27,     29, 35, 37, 41, 42 -   C.I. Reactive Blue 2, 3, 5, 7, 8, 10, 13, 14, 15, 17, 18, 19, 21,     25, 26, 27, 28, 29, 38, 82, 89, 158, 182, 190, 203, 216, 220, 244 -   C.I. Reactive Black 4, 5, 8, 14, 21, 23, 26, 31, 32, 34 -   C.I. Basic Red 12, 13, 14, 15, 18, 22, 23, 24, 25, 27, 29, 35, 36,     38, 39, 45, 46 -   C.I. Basic Violet 1, 2, 3, 7, 10, 15, 16, 20, 21, 25, 27, 28, 35,     37, 39, 40, 48 -   C.I. Basic Yellow 1, 2, 4, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28,     29, 32, 36, 39, 40 -   C.I. Basic Blue 1, 3, 5, 7, 9, 22, 26, 41, 45, 46, 47, 54, 57, 60,     62, 65, 66, 69, 71 -   C.I. Basic Black 8

Besides the above dyes, the dyes disclosed in the following patents can also be used in combination, but the invention is not restricted thereto: WO 01/48090, WO 04/087815, WO 02/090441, WO 03/027185, WO 04/085541, JP-A-2003-321627, JP-A-2002-332418, JP-A-2002-332419, WO 02/059216, WO 02/059215, WO 04/087814, WO 00/58407, Japanese Patents 3558211, 3558212, 3558213, JP-A-2004-323605, and WO 04/104108.

The black ink composition in the invention contains at least two kinds of water-soluble dyes as colorants, and the total amount of the colorants preferably accounts for from 0.5 to 12 wt % in the total weight of the black ink composition, more preferably from 3.0 to 10.0 wt %, and especially preferably from 5.0 to 8.0 wt %.

When the total amount of the dyes contained in the black ink composition is 0.5 wt % or more, and when an image is recorded on a recording medium with this ink composition, sufficiently satisfactory color development and high image density can be obtained.

When the total amount of the dyes contained in the black ink composition is 12 wt % or less, the coefficient of viscosity of the ink composition can be adjusted to a desired value, the ejection amount of the ink composition from the ink jet head can be stabilized, and clogging of the ink jet head can be prevented.

Water-miscible organic solvents that can be used in the ink composition of the invention are materials having functions of a drying preventive, an osmosis accelerator, and a wetting agent, and water-miscible organic solvents having a high boiling point are used. The specific examples of such compounds are disclosed in JP-A-2004-331871, paragraphs [0419] to [0423].

Of water-miscible organic solvents, alcohol-based solvents are especially preferably used in the invention. It is also preferred in the ink composition of invention to contain to contain water-miscible organic solvents having a boiling point of 150° C. or higher.

These water-miscible organic solvents are preferably contained in a total amount of from 5 to 60 mass % in the ink composition, and especially preferably from 10 to 45 mass %.

For the purpose of enhancing the ejection stability of the ink composition of the invention, printing quality, and durability of images, additives such as a surfactant, a drying preventive, an osmosis accelerator, urea-based additives, a chelating agent, an ultraviolet absorber, an antioxidant, a viscosity adjustor, a surface tension adjustor, a dispersant, a dispersion stabilizer, an antiseptic, a mildewproofing agent, an anticorrosion, a pH adjustor, a defoaming agent, a polymer material, an acid precursor, etc., as disclosed in JP-A-2004-331871 can be used by arbitrary selection. The preferred use amount of these additives is as disclosed in JP-A-2004-331871.

In addition to the above components, the black ink composition in the invention can further contain one or more additives selected from the group consisting of a blotting preventive, a bronzing improver, and an ozone-proofness improver, if necessary.

Blotting Preventive:

As a blotting preventive, betaine surfactants are exemplified. The betaine surfactants disclosed in JP-A-2005-111699, paragraphs [0017] to [0044] can be arbitrarily selected and used.

Bronzing Improver:

A bronzing improver for use in the invention has function to weaken or get rid of the bronzing phenomenon that occurs when solid printing is performed with an ink set containing a black ink composition, for example, aromatic compounds having a carboxyl group or salts thereof are exemplified as bronzing improvers.

As the aromatic compounds having a carboxyl group or salts thereof, the compounds disclosed in JP-A-2004-263155, paragraph [0044] can be arbitrarily selected and used.

The total use amount of the aromatic compound having a carboxyl group and/or a salt thereof is determined according to the kind of the aromatic compound having a carboxyl group and/or a salt thereof, the kinds of dyes, and the kind of solvent components.

Further, as other bronzing improvers, colorless and water-soluble plane compounds having more than ten delocalization π electrons in one molecule are preferably used.

As the water-soluble plane compounds, the compounds disclosed in JP-A-2005-105261, paragraphs [0012] to [0026] can be arbitrarily selected and used.

The content of these bronzing improvers is preferably from 0.1 to 10 wt % based on the total weight of the black ink composition, and more preferably the range of from 0.5 to 5 wt %.

Ozone-Proofness Improver:

An ozone-proofness improver is a compound having function of restraining the oxidation of dyes and, for example, thiol-based compounds, amidine-based compounds, carbazide-based compounds, hydrazide-based compounds, guanidine-based compounds are exemplified.

Thiol-Based Compounds:

Thiol-based compounds for use in the invention are compounds having an SH group, and aromatic thiol and aliphatic thiol are preferred, e.g., a compound represented by the following formula (B) is preferred. R₁₀—SH   (B) wherein R₁₀ represents an alkyl group, an aryl group, or a heterocyclic group.

R₁₀ is described below.

As the allyl group, preferably an alkyl group having from 1 to 1 2 carbon atoms, and more preferably from 1 to 6 carbon atoms.

As the aryl group, preferably an aryl group having from 6 to 18 carbon atoms, and more preferably from 6 to 10 carbon atoms.

As the heterocyclic group, a furyl group, a pyridyl group, a pyrimidyl group, a pyrrolyl group, a pyrrolinyl group, a pyrrolidyl group, a dioxolyl group, a pyrazolyl group, a pyrazolinyl group, a pyrazolidyl group, an imidazolyl group, an oxazolyl group, a thiazolyl group, an oxadiazolyl group, a triazolyl group, a thiadiazolyl group, a pyryl group, a pyridyl group, a piperidyl group, a dioxanyl group, a morpholyl group, a pyridazyl group, a pyrazyl group, a piperazyl group, a triazyl group, a trithianyl group, etc., are exemplified.

The substituents represented by R₁₀ include substituents whose hydrogen atoms are further substituted with other arbitrary substituents. Such substituents include a carboxyl group, an oxo group, an amino group, an amino acid residue (preferably having from 2 to 8 carbon atoms), an ammonium group, a hydroxyl group, a thiol group, an alkoxyl group (preferably having from 1 to 12 carbon atoms), an acylamino group (preferably having from 1 to 12 carbon atoms, the carboxyl group and the amino group may be substituted), a carbamoyl group, etc., are exemplified, and two or more of these substituents may be substituted on the same molecule.

As the synthesizing method of the compound represented by formula (B), e.g., by the reaction of applicable aryl Grignard's reagent and single sulfur, thiol wherein R₁₀ is an aryl group is obtained, and by the reaction of applicable halogenated alkyl and sodium hydrogensulfide or thiourea, thiol wherein R₁₀ is an aryl group is obtained. Amidine-based compounds:

Amidine-based compounds for use in the invention are compounds having a structure in which —C(═NH)—NH₂ group (an amidino group) is bonded to the carbon atom of the group containing a carbon atom, and one or more hydrogen atoms of the —C(═NH)—NH₂ group may be substituted with substituents.

An amidine-based compound represented by the following formula (C) is preferably used.

In formula (C), R₅₁, R₅₂, R₅₃ and R₅₄ each represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group, and when R₅₁ contains a nitrogen atom, the nitrogen atom is not bonded to C shown in the formula.

The alkyl group is an alkyl group preferably having from 1 to 12 carbon atoms, and more preferably from 1 to 6 carbon atoms.

The aryl group is an aryl group preferably having from 6 to 18 carbon atoms, and more preferably from 6 to 10 carbon atoms.

As the heterocyclic group, a fill group, a pyridyl group, a pyrimidyl group, a pyrrolyl group, a pyrrolinyl group, a pyrrolidyl group, a dioxolyl group, a pyrazolyl group, a pyrazolinyl group, a pyrazolidyl group, an imidazolyl group, an oxazolyl group, a thiazolyl group, an oxadiazolyl group, a triazolyl group, a thiadiazolyl group, a pyryl group, a pyridyl group, a piperidyl group, a dioxanyl group, a morpholyl group, a pyridazyl group, a pyrazyl group, a piperazyl group, a triazyl group, a trithianyl group, etc., are exemplified.

The hydrogen atoms of the substituents represented by R₅₁ to R₅₄ may further be substituted with arbitrary other substituents. As such substituents, a halogen atom, e.g., chlorine, a nitro group, an amino group, a carboxyl group, a carbamoyl group, an amidino group, an aryloxy group (the aryl moiety may further be substituted with any substituents enumerated here), etc., are exemplified, and two or more of these substituents may be substituted on the same molecule. The hydrogen atoms of the above amino group, carbamoyl group, and amidino group may be substituted with the alkyl group, aryl group or heterocyclic group represented by R₅₁ to R₅₄.

The amidine-based compound may take the form of a salt, such as hydrochloride.

The compound represented by formula (C) can be obtained at least by the process of acting ammonia on the applicable hydrochloride of iminoether. Carbazide-based compounds:

Carbazide-based compounds for use in the invention are carbazide and derivatives thereof, and a compound represented by the following formula (D) is used. R₅₅R₅₆NCONHNR₅₇R₅₈   (D)

In formula (D), R₅₅ to R₅₈ each represents a hydrogen atom or an organic group.

As the organic group, the organic groups represented by R₅₁ to R₅₄ above are preferred

The substituents represented by R₅₅ to R₅₈ include substituents the hydrogen atoms of which are further substituted with other arbitrary substituents. As such substituents, in addition to those capable of being substituted with R₅₁ to R₅₄ exemplified above, —NHCONHNR₅₉R₆₀ (where R₅₉ and R₆₀ each represents an organic group, and the preferred examples are the same as R₅₁ to R₅₄) is preferably exemplified. In the invention, —NHCONHNR₅₉R₆₀ is called a carbazide structure. The carbazide-based compounds for use in the invention have preferably 2 or more (more preferably from 2 to 6) carbazide structures in the same molecule.

The carbazide-based compound represented by formula (D) can be obtained specifically by condensation reaction of applicable isocyanate or diisocyanate, urea derivatives, etc., with hydrazine compounds represented by NH₂NR₅₇R₅₈ (where R₅₇ and R₅₈ are the same as above).

Hydrazide-Based Compounds:

Hydrazide-based compounds for use in the invention are hydrazide and derivatives thereof, and a compound represented by the following formula (E) is used. R₆₁CONHNR₆₂R₆₃   (E)

In formula (E), R₆₁, R₆₂ and R₆₃ each represents a hydrogen atom, a hydrazino group, or an organic group; R₆₁ and R₆₂ or R₆₃ may be bonded to form a ring.

As the organic group, the organic groups exemplified in R₅₁ to R₅₄ in formula (C) are preferred.

The substituents represented by R₆₁ to R₆₃ include substituents the hydrogen atoms of which are further substituted with other arbitrary substituents. As such substituents, in addition to those capable of being substituted with R₅₁ to R₅₄ exemplified above, an acyl group, a cyano group, an alkoxyl group, an aralkyloxy group, a benzoyloxy group, —NHCONHNR₆₄R₆₅ (where R₆₄ and R₆₅ each represents an organic group, and the preferred examples are the same as R₅₁ to R₅₄) is preferably exemplified. In the invention, —NHCONHNR₆₄R₆₅ is called a hydrazide structure. The hydrazide-based compounds for use in the invention have preferably 2 or more (more preferably from 2 to 6) hydrazide structures in the same molecule.

The hydrazide-based compound represented by formula (E) can be obtained specifically by condensation reaction of applicable acid derivatives or acid anhydrides such as carboxylic acid ester or acid halide, etc., with a hydrazine compound represented by NH₂NR₆₂R₆₃ (where R₆₂ and R₆₃ are the same as above).

Of the ozone-proofness improvers, guanidine-based compounds are especially preferred. Guanidine-based compounds are described in detail below.

Guanidine-Based Compounds:

Guanidine-based compounds for use in the invention are compounds having an N—C(═N)—N structure.

As guanidine-based compounds, a compound represented by the following formula (F) is preferred.

In formula (F), R₇₁, R₇₂, R₇₃ and R₇₄ each represents a hydrogen atom, an alkyl group, an alkoxyl group, an aryl group, a heterocyclic group, or an amino group; and R₇₅ represents a hydrogen atom, an alkyl group, an alkoxyl group, an aryl group, or a heterocyclic group. These alkyl group, alkoxyl group, aryl group, heterocyclic group, or amino group may be substituted or may not substituted.

The alkyl group is an alkyl group preferably having from 1 to 12 carbon atoms, and especially preferably from 1 to 6 carbon atoms.

The alkoxyl group is an alkoxyl group preferably having from 1 to 12 carbon atoms, and especially preferably from 1 to 6 carbon atoms.

The aryl group is an aryl group preferably having from 6 to 18 carbon atoms, and especially preferably from 6 to 10 carbon atoms.

As the heterocyclic group, a furyl group, a pyridyl group, a pyrimidyl group, a pyrrolyl group, a pyrrolinyl group, a pyrrolidyl group, a dioxolyl group, a pyrazolyl group, a pyrazolinyl group, a pyrazolidyl group, an imidazolyl group, an oxazolyl group, a thiazolyl group, an oxadiazolyl group, a triazolyl group, a thiadiazolyl group, a pyryl group, a pyridyl group, a piperidyl group, a dioxanyl group, a morpholyl group, a pyridazyl group, a pyrazyl group, a piperazyl group, a triazyl group, a trithianyl group, etc., arc exemplified.

The hydrogen atoms of the alkyl group, alkoxyl group, aryl group or heterocyclic group represented by R₇₁ to R₇₅ may further be substituted with arbitrary other substituents. As such substituents, a halogen atom, e.g., chlorine, a nitro group, an amino group, a carboxyl group, a hydroxyl group, a carbamoyl group, an amidino group, a guanidino grouup, an aryloxy group (the aryl moiety may further be substituted with any substituents enumerated here), etc., are exemplified, and two or more of these substituents may be substituted on the same molecule. The hydrogen atoms of the above amino group, carbamoyl group, amidino group and guanidino group may be substituted with the alkyl group, alkoxyl group, aryl group or heterocyclic group represented by R₇₁ to R₇₅.

The hydrogen atoms of the amino group represented by R₇₁ to R₇₄ may further be substituted with the alkyl group, alkoxyl group, aryl group or heterocyclic group represented by R₇₁ to R₇₅.

The guanidine-based compounds may be in the form of a salt or a metal complex, for example, hydrochloride, nitrate, phosphate, sulfamate, carbonate, acetate, etc., are exemplified.

The compound represented by formula (F) can be obtained at least by the process of acting ammonia on the applicable hydrochloride of iminoether.

The guanidine-based compounds may be polymers having an N—C(═N)—N structure. As such polymers, compounds containing a repeating unit represented by the following formula (F-a), (F-b) or (F-c), but the invention is not restricted thereto. The compounds containing the repeating unit may be oligomers. The compounds containing the repeating unit represented by formula (F-c) may be monomers. These compounds are preferably salts with acids.

In formula (F-a), R₇₅ has the same meaning as above; R₇₆ represents any of R₇₁, R₇₂, R₇₃ and R₇₄, and n of R₇₅ and R₇₆ may be the same or different; and n7 represents an integer of 2 or more, preferably from 2 to 30, and more preferably from 2 to 15. The compound containing the repeating unit represented by formula (F-a) may be a homopolymer, or may be a copolymer with other repeating unit, e.g., azetidinium, etc. The terminal structure can be arbitrarily selected, but a hydrogen atom, an alkyl group, an alkoxyl group, an aryl group, a heterocyclic group or an amino group is preferred.

In formula (F-b), R₇₅ and R₇₆ have the same meaning as above, and l7 of R₇₅ and R₇₆ may be the same or different. l7 is an integer of 2 or more, preferably from 2 to 10, and more preferably from 2 to 5. m7 is an integer of 1 or more, preferably from 1 to 6, and more preferably from 1 to 3. The compound containing the repeating unit represented by formula (F-b) may be a homopolymer, or may be a copolymer with other repeating unit, e.g., azetidinium, etc. The terminal structure can be arbitrarily selected, but a hydrogen atom, an alkyl group, an alkoxyl group, an aryl group, a heterocyclic group or an amino group is preferred.

In formula (F-c), R₇₅ has the same meaning as above; R₇₇ has the same meaning as R₇₁ or R₇₂; R₇₆ has the same meaning as R₇₃ or R₇₄, and p7 of R₇₅, R₇₆ and R₇₇ maybe be the same or different. p7 is an integer of 1 or more, preferably from 1 to 10, and more preferably from 1 to 5. The compound containing the repeating unit represented by formula (F-c) may be a homopolymer, or may be a copolymer with other repeating unit, e.g., azetidinium, etc. The terminal structure can be arbitrarily selected, but a hydrogen atom, an alkyl group, an alkoxyl group, an aryl group, a heterocyclic group or an amino group is preferred.

These various compounds can be used alone or in combination as the ozone-proofness improver, and the use amount is preferably from 0.1 to 10 mass % in the black ink composition.

The coefficient of viscosity of the black ink composition in the invention is preferably from 1 to 20 mPa·s, more preferably from 2 to 15 mPa·s, and especially preferably from 2 to 10 mPa·s. When the coefficient of viscosity exceeds 20 mPa·s, the fixing speed of a recorded image lowers and the ejecting property also lowers. When the viscosity is less than 1 mPa·s, a recorded image blots and grade is deteriorated. The coefficient of viscosity is measured at 25° C. The coefficient of viscosity is adjusted with the viscosity adjustor. The addition amount of a water-miscible organic solvent is, in the case of ink jet recording, preferably from 5 to 70 mass % to the black ink composition, and more preferably from 10 to 60 mass %. Water-miscible organic solvent can be used in combination of two or more kinds.

A measuring method of the coefficient of viscosity of a liquid is described in detail in JIS Z8803, but it can be measured easily with a commercially available viscometer. For instance, B type viscometer and E type viscometer (manufactured by Tokyo Keiki Co) are known as a rotary type. In the invention, viscosity was measured with an oscillating type MV-100A-L type (manufactured by YAMAICHI ELECTRONICS Co., Ltd.) at 25° C.

The black ink composition in the invention preferably has surface tension of from 20 to 50 mN/m, and more preferably from 20 to 40 mN/m.

Surface tension means both dynamic surface tension and static surface tension, and both are measured at 25° C. When the surface tension is higher than 50 mN/m, ejection stability lowers, blotting occurs at color mixing time and the qualities of printed characters conspicuously deteriorate such that whiskers appear. When the surface tension of ink is lower than 20 mN/m, printing failure sometimes occurs due to adhesion of the ink to the surface of hardware. Surfactants can be used for the adjustment of surface tension, and the above-described surfactants can be used.

As measuring methods of static surface tension, a capillary rise method, a dropping method and a suspension lug method arc known. A vertical panel method is used in measuring static surface tension in the invention.

When a part of a thin panel of glass or platinum is immersed in a liquid and hung vertically, the surface tension of the liquid works downward along the length where the liquid and the panel are in contact. Static surface tension can be measured with equilibrating this force by upward force.

As measuring methods of dynamic surface tension, a oscillation jet method, a meniscus dropping method, and a maximum bubble pressure method as described in Shin-Jikken Kagaku Koza (New Experimental Chemistry), Vol. 18, “Kaimen to Colloid (Interface and Colloid)”, pp. 69 to 90, Manizen Co. (1977) are known, further, as disclosed in JP-A-3-2064, a liquid film breaking method is known. In the invention, a bubble pressure differential pressure method is used for the measurement of dynamic surface tension. The principle of the measurement and measuring method are described below.

When bubbles are formed in a stirred and homogenized solution, new air-liquid interface is formed and surfactant molecules in the solution gather on the surface of the solution at a constant velocity. When a bubble rate (generating velocity of bubbles) is changed, if generating velocity slows down, more molecules of the surfactant gather on the surfaces of bubbles, thus the maximum bubble pressure just before breaking of bubbles becomes small and the maximum bubble pressure (surface tension) to the bubble rate can be detected. As the preferred measuring method of dynamic surface tension, a method of generating bubbles in a solution with two probes, large and small, measuring the differential pressure of two probes at the state of maximum bubble pressure, and computing the dynamic surface tension can be exemplified.

The conductivity of the black ink composition in the invention is preferably from 0.01 to 10 S/m, and particularly preferably from 0.05 to 5 S/m. The conductivity is measured at 25° C. By making the conductivity the above range, image stability can be secured.

The conductivity can be measured by an electrode method using commercially available saturated potassium chloride.

The conductivity can be controlled primarily by the ion concentration in an aqueous solution. When the concentration of salt is high, desalinization can be performed through an ultrafiltration membrane. When conductivity is controlled by the addition of salts, control can be done by the addition of various organic and inorganic salts.

As the inorganic salts, inorganic compounds, e.g., potassium halide, sodium halide, sodium sulfate, potassium sulfate, sodium hydrogensulfate, potassium hydrogensulfate, sodium nitrate, potassium nitrate, sodium hydrogencarbonate, potassium hydrogencarbonate, sodium phosphate, sodium monohydrogenphosphate, boric acid, potassium dihydrogen-phosphate, sodium dihydrogenphosphate, etc., and organic compounds, e.g., sodium acetate, potassium acetate, potassium tartrate, sodium tartrate, sodium benzoate, potassium benzoate, sodium p-toluenesulfonate, potassium caccharinate, potassium phthalate, sodium picolinate, etc., can be used.

The conductivity can also be controlled by the selection of the above-described additives.

The pH of the black ink composition in the invention is preferably from 7 to 9, and more preferably from 7 to 8. When the pH is less than 7, the solubility of dye lowers and nozzles are liable to generate clogging, while when the pH is higher than 9, a waterproof property is liable to deteriorate. pH can be measured with commercially available test paper, or can be measure by an electrode method with saturated potassium chloride.

The pH of the black ink composition can be adjusted with the pH adjustor.

It is possible to use the black ink composition in the invention in various image recordings for its high image durability. As the materials for imaging, for example, utilization for photographic photosensitive materials, utilization for heat transfer materials, utilization for heat-sensitive/pressure-sensitive materials, and utilization for ink jet recording are possible, and of these uses, utilization as black ink composition for ink jet recording is most preferred.

Manufacturing methods of ink compositions for ink jet recording are disclosed in detail in each of JP-A-5-148436, JP-A-5-295312, JP-A-7-97541, JP-A-7-82515, JP-A-7-118584, and JP-A-2004-331871, and these methods can be used in the manufacture of the ink composition in the invention.

As the recording papers and recording films that arc printing media preferably used in the invention, those disclosed in JP-A-2004-331871 (paragraphs [0503] to [0627]) are preferably used.

In the manufacture of ink, ultrasonic vibration can be included in a dissolution process of additives such as dyes as disclosed in JP-A-2004-331871.

In manufacturing ink in the invention, a process of removal of residua that are solids content by filtration carried out after preparation of ink is important. The filtration process is also disclosed in JP-A-2004-331871

The black ink composition in the invention can be used not only for forming a monochrome image but also a full color image. For forming a full color image, an ink set preferably contains at least the ink compositions of yellow, magenta and cyan, and a plurality of ink compositions that arc the same in hue and different in density can also be used with respective colors. Further, red, green, blue, and intermediate tone ink composition such as violet can also be used.

The examples of dyes as the colorants contained in the ink composition that can be preferably used in the ink set in the invention arc shown below, but the invention is by no means restricted thereto.

Yellow Dye:

As yellow dyes, those disclosed in WO 05/075573, JP-A-2004-83903 (paragraphs [0024] to [0062]), JP-A-2003-277661 (paragraphs [0021] to [0050]), JP-A-2003-277662 (paragraphs [0042] to [0047]), JP-A-2003-128953 (paragraphs [0025] to [0076]), JP-A-200341160 (paragraphs [0028] to [00641), U.S. Patent Application U.S. 2003/0213405 (paragraph [0108]), and a compound represented by the following formula (Y-1) are exemplified.

In formula (Y-1), G represents a heterocyclic group, and n represents an integer of from 1 to 3. When n is 1, R, X, Y, Z, Q and G each represents a monovalent group. When n is 2, R, X, Y, Z, Q and G each represents a monovalent or divalent substituent, and at least one represents a divalent substituent. When n is 3, R, X, Y, Z, Q and G each represents a monovalent, divalent or trivalent substituent, and at least two represent a divalent substituent or at least one represents a trivalent substituent.

The compound represented by formula (Y-1) is preferably a compound represented by any of the following formulae (Y-2), (Y-3), (Y4), (Y-5) and (Y-6).

In formula (Y-2), R₁, R₂, X₁, X₂, Y₁, Y₂, Z₁ and Z₂ each represents a monovalent group; G represents an atomic group to constitute a 5- to 8-membered nitrogen-containing heterocyclic ring; M represents a hydrogen atom or a cation; and m₁ represents an integer of from 0 to 3.

In formula (Y-3), R₁, R₂, R₁₁, R₁₂, X₁, X₂, Z₁ and Z₂ each represents a monovalent group; L₁ represents a divalent linking group; G₁ and G_(2 a) each represents an atomic group to constitute a 5- to 8-membered nitrogen-containing heterocyclic ring; M represents a hydrogen atom or a cation; and m₂₁ and m22 each represents an integer of from 0 to 3.

In formula (Y-4), R₁, R₂, R₁₁, R₁₂, X₁, X₂, Y₁ and Y₂ each represents a monovalent group; L₂ represents a divalent linking group; G₁ and G₂ each represents an atomic group to constitute a 5- to 8-membered nitrogen-containing heterocyclic ring; M represents a hydrogen atom or a cation; and m₃₁ and m₃₂ each represents an integer of from 0 to 3.

In formula (Y-5), R₁₁, R₁₂, X₁, X₂, Y₁, Y₂, Z₁ and Z₂ each represents a monovalent group; L₃ represents a divalent linking group; G₁ and G₂ each represents an atomic group to constitute a 5- to 8-membered nitrogen-containing heterocyclic ring; M represents a hydrogen atom or a cation; and m₄₁ and m₄₂ each represents an integer of from 0 to 3.

In formula (Y-6), R₁, R₂, R₁₁, R₁₂, Y₁, Y₂, Z₁ and Z₂ each represents a monovalent group; L₄ represents a divalent linking group; G₁ and G₂ each represents an atomic group to constitute a 5- to 8-membered nitrogen-containing heterocyclic ring; M represents a hydrogen atom or a cation; and m₅₁ and m₅₂ each represents an integer of from 0 to 3.

In formulae (Y-2), (Y-3), (Y-4), (Y-5) and (Y-6), the nitrogen-containing heterocyclic ring constituted of G, G₁ and G₂ is preferably an S-triazine ring.

The specific examples of the compounds represented by formulae (Y-1), (Y-2), (Y-3), (Y-4), (Y-5) and (Y-6) (Exemplified Dyes 1 to 26) are shown below, but the dyes used in the invention are not restricted to these compounds.

The structures of the following specific examples are shown in the form of a free acid, but of course the compounds may be used in the form of an arbitrary salt.

As preferred counter cations, an alkali metal (e.g., lithium, sodium, potassium), ammonium, and an organic cation (c.g., pyridinium, tetramethylammoniun, guanidinium) can be exemplified.

Magenta Dye:

As magenta dyes, heterocyclic azo dyes are preferred, and the compounds disclosed in WO 02/83795 (pages 35-55), WO 02/83662 (pages 27-42), JP-A-2004-149560 (paragraphs [0046] to [0059]), JP-A-2004-149561 (paragraphs [0047] to [0060]), and an azo dyestuff represented by the following formula (M-1) are exemplified.

In formula (M-1), A represents the residue of a 5-membered heterocyclic diazo component A-NH₂; B₃₁ and B₃₂ each represents —CR₈₁═ or —CR₈₂═, or either one represents a nitrogen atom and the other represents —CR₈₁═ or —CR₈₂═; R₈₃ and R₈₄ each represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, or a sulfamoyl group, and each group may further have a substituent; R₈₁ and R₈₂ each represents a hydrogen atom, a halogen atom, an aliphatic group, an aromatic group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group, a hydroxyl group, an alkoxyl group, an aryloxy group, a silyloxy group, an acyloxy group, a carbamoyl group, a heterocyclic oxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, an alkylamino group, an arylamino group, a heterocyclic amino group, an acylamino group, a ureido group, a sulfamoylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, an aryloxycarbonylamino group, a nitro group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, an alkylsulfinyl group, an arylsulfinyl group, a sulfamoyl group, a sulfo group, or a heterocyclic thio group, and each group may further be substituted, and R₈₁ and R₈₃, or R₈₃ and R₈₄ may be bonded to form a 5- or 6-membered ring; a and e each represents an alkyl group, an alkoxyl group, or a halogen atom, when a and e both represent an alkyl group, the total number of carbon atoms constituting the alkyl group is 3 or more, and they may be further substituted; b, c and d each has the same meaning as R₈₁ and R², and a and b, or e and d, may be condensed with each other, provided that formula (M-1) has at least one ionic hydrophilic group.

A represents the residue of a 5-membered heterocyclic diazo component A-NH₂. As the examples of the hetero atoms of the 5-membered heterocyclic ring, N, O and S are exemplified. The 5-membered heterocyclic ring is preferably a nitrogen-containing 5-membered heterocyclic ring, and an aliphatic ring, an aromatic ring, or other heterocyclic ring may be condensed with the heterocyclic ring.

The preferred examples of the heterocyclic rings represented by A include a pyrazole ring, an imidazole ring, a triazole ring, a thiazole ring, an isothiazole ring, a thiadiazole ring, a benzothiazole ring, a benzoxazole ring, and a benzisothiazole ring. Each heterocyclic ring may further have a substituent. Of these heterocyclic rings, a pyrazole ring, an imidazole ring, an isothiazole ring, a thiadiazole ring, a benzothiazole ring, and a triazole ring are preferred.

The azo dyestuff represented by the formula (M-1) is preferably represented by the following formula (M-2).

In formula (M-2), Z₁₁ represents an electron attracting group having a Hammett's substitution constant σp value of 0.20 or more; Z₁₂ represents a hydrogen atom, an acyl group, an aliphatic group, an aromatic group, or a heterocyclic group; R₈₁, R₈₂, R₈₃, R₈₄, a, b, c, d and e each the same meaning as in formula (M-1); and Q₁₁ represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group. Each of Z₁₁, Z₁₂ and Q₁₁ may further have a substituent, provided that formula (M-2) has at least one ionic hydrophilic group.

The specific examples of azo dyestuffs are shown below, but the invention is not restricted thereto.

Cpd. X R¹ R² R³ R⁴ a b c d e a-1 CH₃ CN CH₃ H

CH₃ H SO₃H H C₂H₅ a-2 ″ CONH₂ H ″

iPr ″ ″ ″ iPr a-3 ″ H CH₃

″ ″ ″ ″ ″ ″ a-4 ″ ″ ″ ″

C₂H₅ ″ ″ ″ C₂H₅ a-5 ″ ″ ″ ″

″ ″ CH₃ SO₃H ″

Cpd. X R¹ R² R³ R⁴ a b c d e b-1 —SCH₃ CN CH H

CH₃ H SO₃H H C₂H₅ b-2

CONH₂ H ″

iPr ″ ″ ″ iPr b-3

H CH₃

″ ″ ″ ″ ″ ″ b-4

″ ″ ″

C₂H₅ ″ ″ ″ C₂H₅ b-5 —SCH₃ ″ ″ ″

″ ″ CH₃ SO₃H ″

Cpd. X R¹ R² R³ R⁴ a b c d e c-1 5-Cl CN CH₃ H

CH₃ H SO₃H H C₂H₅ c-2 5,6-diCl CONH₂ H ″

iPr ″ ″ ″ iPr c-3 5-CH₃ H CH₃

″ ″ ″ ″ ″ ″ c-4 6-Cl ″ ″ ″

C₂H₅ ″ ″ ″ C₂H₅ c-5 5,6-diCl ″ ″ ″

″ ″ CH₃ SO₃H ″

Cpd. X Q R¹ R² R³ R⁴ a b c d e d-1

CN CH₃ H

CH₃ H SO₃H H C₂H₅ d-2 t-Bu ″ CONH₂ H ″

iPr ″ ″ ″ iPr d-3 ″ ″ H CH₃

″ ″ ″ ″ ″ ″ d-4 ″ ″ ″ ″ ″

C₂H₅ ″ ″ ″ C₂H₅ d-5 ″ ″ ″ ″ ″

″ ″ CH₃ SO₃H ″

Cpd. X Q R¹ R² R³ d-6 t-Bu

H CH₃

d-7 ″ ″ ″ ″ ″ d-8 ″ ″ ″ ″ ″ d-9 ″

″ ″

d-10 ″ ″ ″ ″ ″ Cpd. R⁴ a b c d e d-6

CH₃ H SO₃H H iPr d-7

″ ″ ″ ″ OCH₃ d-8

″ ″ CH₃ SO₃H Cl d-9

C₂H₅ ″ ″ ″ C₂H₅ d-10

iPr ″ SO₃H ″ iPr

Cpd. Q B₁ B₂ R³ d-11

N C—CH₃ H d-12

″

″ d-13 ″ C—H N ″ d-14

C—H N

d-15 ″ N

″ Cpd. R⁴ a b c d e d-11

C₂H₅ H CH₃ SO₃H C₂H₅ d-12 ″ ″ ″ ″ ″ ″ d-13

iPr ″ SO₃H H iPr d-14

CH₃ ″ ″ ″ C₂H₅ d-15 ″ ″ ″ ″ ″ ″

Cpd. X Q R¹ R² R³ R⁴ a b c d e d-16 t-Bu

H CH₃

C₂H₅ H CH₃ SO₃H C₂H₅ d-17 ″

″ ″

″ ″ ″ ″ ″ d-18 ″ ″ ″ ″

″ ″ ″ ″ ″ d-19 ″

″ ″

″ ″ ″ ″ ″ ″ d-20 ″

″ ″

″ ″ ″ ″ ″ ″ Cyan Dye:

As phthalocyanine dye is preferred as cyan dye, and associating phthalocyaninc dyes are preferred. As the associating phthalocyanine dyes, those having an associating group are preferred. The associating group means a group at least having a bonding site (Or a functional group) capable of hydrogen bonding between molecules at least in the group. The bonding site can be present one or more in one group. As the bonding sites, a hydroxyl group, an amino group, an amido bond, an oxide bond, etc., are exemplified, and hydrogen bonding is formed between the same kind or different kinds. The associating group may be one capable of hydrogen bonding between a phthalocyanine dye and an arbitrary additive.

For reducing the reactivity with ozone that is an electrophilic agent, it is preferred to make oxidation potential 1.0 V (vs SCE) or nobler by partially substituting the carbon atom of a phthalocyanine skeleton with a hetero atom, e.g., azaphthalocyanine, or by introducing an electron attracting group into a phthalocyanine skeleton. The nobler, the more preferred is the oxidation potential. The oxidation potential is more preferably 1.1 V (vs SCE) or nobler, and especially preferably 1.15 V (vs SCE) or nobler.

As associating phthalocyanine dyes, those disclosed in WO 02/60994, WO 03/811, WO 03/62324, JP-A-2003-213167, JP-A-2004-75986, JP-A-2004-323605, JP-A-2004-315758, JP-A-2004-315807 and JP-A-2005-179469 are exemplified.

Besides the above patents, phthalocyanine dyes can be synthesized according to JP-A-2004-315729,JP-A-200541856 and JP-A-2004-323511. Further, starting materials, dye intermediates, and synthesis route are not restricted thereto.

The ink set in the invention can also be used for uses other than ink jet recording. For example, the ink set can be used as materials for display image, image-forming materials of interior decoration, and image-forming materials of outdoor decoration as disclosed in JP-A-2004-331871, paragraphs [0727] to [0731].

Besides the above dyes, the dyes disclosed in the following patents can also be preferably used in ink composition of each color: JP-A-10-130557, JP-A-9-255906, JP-A-6-234944, JP-A-7-97541, EP 982371, WO 00/43450, WO 00/43451, WO 00/43452, WO 00/43453, WO 03/106572, WO 03/104332, JP-A-2003-238862, JP-A-2004-83609, JP-A-2002-302619, JP-A-2002-327131, JP-A-2002-265809, WO 01/48090, WO 04/087815, WO 02/00-441, WO 03/027185, WO 04/085541, JP-A-2003-321627, JP-A-2002-332418, JP-A-2002-332419, WO 02/059216, WO 02/059215, WO 04/087814, WO 04/046252, WO 04/046265, Japanese Patent 3479444, U.S. Pat. No. 6,652,637B, WO 03/106572, WO 03/104332, WO 00/58407, Japanese Patent 3558211, Japanese Patent 3558212, Japanese Patent 3558213, JP-A-2004-285351, JP-A-2004-323605, and WO 04/104108.

Recording Method:

The recording method in the invention is to adhere the ink composition of the invention to a recording material. The preferred recording method in the invention is an ink jet recording method of performing recording by ejecting the droplets of the ink composition onto a recording medium by imparting energy to the ink composition to form an image on known image-receiving materials as materials to be recorded, that is, plane paper and resin coat paper, e.g., special paper for ink jet recording, films, electrophotographic common paper, napkin, glass, metal, ceramics, etc., as disclosed in JP-A-8-169172, JP-A-8-27693, JP-A-2-276670, JP-A-7-276789, JP-A-9-323475, JP-A-62-238783, JP-A-10-153989, JP-A-10-217473, JP-A-10-235995, JP-A-10-337947, JP-A-10-217597, and JP-A-10-337947. The description in JP-A-2003-306623, paragraphs [0093] to [0105] can be applied to the ink jet recording method in the invention.

In forming an image, polymer latex compounds may be used in combination for the purpose of providing glossiness and a waterproof property, and improving a weather resisting property. The time of applying polymer latex compounds to an image-receiving material may be any time before, after, or at the same time with the addition of colorants, accordingly the plate of addition may be in image-receiving paper, in ink, or may be used as a liquid material of a polymer latex alone.

Specifically, the methods disclosed in JP-A-2002-166638, JP-A-2002-121440, JP-A-2002-154201, JP-A-2002-144696, JP-A-2002-080759, JP-A-2002-187342 and JP-A-2002-172774 can be preferably used.

Recording paper and recording film for use in ink jet printing with the ink of the invention are described below. The supports in recording paper and recording film comprise chemical pulp, e.g., LBKP, NBKP, etc., mechanical pulp, e.g., GP, POW, RMP, TMp, CTMP, CMP, CGP, etc., and wastepaper pulp, e.g., DIP, etc., and manufactured by adding various additives, according to necessity, e.g., a conventionally known pigment, a binder, a sizing agent, a fixing agent, a cationic agent, and a paper strength increasing agent, and made with various paper machines, e.g., Fourdrinier machine and cylinder paper machine. Other than these supports, synthetic paper and a plastic film sheet can be used as supports. The thickness of a support is preferably from 10 to 250 μm and weight is from 10 to 250 g/m². An ink-receiving layer and a back coat layer may be directly provided on a support, or an ink-receiving layer and a back coat layer may be provided after providing size press or an anchor coat layer with starch and polyvinyl alcohol. A support may be subjected to flattening treatment with calendering apparatus, e.g., machine calender, TG calender or soft calender. In the invention as supports, paper and plastic film both surfaces of which arc laminated with polyolefin (e.g., polyethylene, polystyrene, polyethylene terephthalate, polybutene and copolymers thereof) are more preferably used. It is preferred to add white pigments (c.g., titanium oxide, zinc oxide) or toning dyes (e.g., cobalt blue, ultramarine, neodymium oxide) to polyolefin.

An ink-receiving layer provided on a support contains a pigment and an aqueous binder. The pigment is preferably a white pigment The examples of white pigments include white inorganic pigments, e.g., calcium carbonate, kaolin, talc, clay, diatomaceous earth, synthetic amorphous silica, aluminum silicate, magnesium silicate, calcium silicate, aluminum hydroxide, alumina, lithopone, zeolite, barium sulfate, calcium sulfate, titanium dioxide, zinc sulfide, zinc carbonate, etc., and organic pigments, e.g., styrene-based pigments, acrylic-based pigments, urea resins melamine resins, etc. As white pigments contained in an ink-receiving layer, porous inorganic pigments are preferred, and synthetic amorphous silica having a large pore area is especially preferred. As synthetic amorphous silica, both of silicic anhydride manufactured by a dry manufacturing method and hydrous silicic acid manufactured by a wet manufacturing method can be used, but it is especially preferred to use hydrous silicic acid.

In the recording method of the invention, methods of ink jet recording are not restricted, and the ink or ink set of the invention can be used in known systems, for example, an electrical charge controlling system of making use of electrostatic induction force and ejecting ink droplets, a system of using ink jet heads of forming ink droplets by mechanical deformation of electrostrictive elements, a drop on demand system (a pressure pulse system) of utilizing vibratory pressure of piezo-elements, an acoustic ink jet system of converting electric signal to acoustic beam and irradiating ink, and ejecting ink droplets by making use of the radiation pressure, and a thermal ink jet system of heating ink to thereby generate bubbles, and ejecting ink droplets by utilizing the generated pressure. Ink jet recording systems include a system of ejecting a great number of minute volumes of ink droplets of so-called photo-ink of low density, a system of improving image quality by using a plurality of inks having substantially the same hue and different densities, and a system of using colorless and transparent ink.

EXAMPLE

The invention will be described with reference to examples, but the invention is by no means restricted thereto.

Manufacture of Ink Stock Solution:

To 50 g of dye Black-6 was added 850 g of ultrapure water (specific resistance value: 18 MΩ·cm or more), and the mixture was stirred by heating at 60 to 65° C. for 1 hour with heating. After the dye was thoroughly dissolved, the temperature was lowered to room temperature, and 100 g of 2-pyrrolidone as a viscosity reducing agent, and 1.0 g of PROXEL XL2 as an antiseptic were added to the solution. After stirring for 10 minutes, the solution was filtered rough a microfilter having an average pore size of 0.2 μm under reduced pressure to prepare an ink stock solution.

Preparation of Black Ink:

After adding ultrapure water (specific resistance value: 18 MΩ·cm or more) to the following components to make 100%, each mixture was stirred by heating at 30 to 40° C. for 1 hour. The resulted solution was then filtered through a microfilter having an average pore size of 0.25 μm under reduced pressure to prepare each black ink solution. In Table 1 below, the numerical value of each component is shown in wt % taking the mass of the ink composition as 100%, and “the rest” that shows the amount of water means the amount making 100% in total with the components other than water. TABLE 1 B-1 B-2 B-3 B-4 B-5 B-6 B-7 B-8 B-9 B-10 Black-1 4 4 4 3 3 3 6 Black-2 3 2 6 Black-3 2 3 3 6 Black-4 2 Black-5 3 Black-7 3 Black-6 Ink stock solution 30 Glycerol 10 10 10 10 10 10 10 10 10 10 Triethylene glycol 2 2 2 2 2 2 2 2 2 2 TEGmBE 8 8 8 8 8 8 8 8 8 8 Sarfinol 465 (*1) 1 1 1 1 1 1 1 1 1 1 Urea 5 3 3 3 3 3 3 3 3 3 1,2-Hexanediol 3 3 3 3 3 3 3 3 3 3 Bronzing inhibitor I 1 PROXEL XL2 (*2) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Water The rest The rest The rest The rest The rest The rest The rest The rest The rest The rest Unit: wt % (*1) Manufactured by Air Products and Chemical, Inc. (*2) Manufactured by Abesia Water-Soluble Long Wave Dye L Represented by Formula (L-1):

Water-Soluble Long Wave Dye L Represented by Formula (L-8):

Water-Soluble Long Wave Dye L Represented by Formula (L-7):

Water-Soluble Long Wave Dye L Represented by Formula (L6):

Water-Soluble Short Wave Dye S:

Water-Soluble Long Wave Dye L Represented by Formula (L-6a):

Example 1

These black inks were filled in black ink cartridges of Ink Jet Printer PM-A700 (manufactured by SEIKO EPSON CORPORATION). A gray image whose density changed stepwise from R:0, G:0, B:0 to R:255, G:255, B:255 (hereinafter referred to as step pattern) was made with imaging software Photoshop (manufactured by Adobe Systems Incorporated), printed in “black” mode, and an image printed with black ink alone was obtained. As the image-receiving sheet, photographic paper (glossy paper) (manufactured by SEIKO EPSON CORPORATION) was used.

Evaluation:

1) The hue was evaluated by visually observing gray tone in each printed density in gray step pattern. The hue that shows preferred gray tone in each density is graded A, the hue where density of losing gray balance here and there is found is graded B, and the hue where almost all the densities lose gray balance is graded C.

2) Regarding image density, Dvis of a black solid image (image data, R:0, G:0, B:0 part) was measured with densitometer X-rite 310.

The case where Dvis is 2.4 or more is graded A, 2.3 or more and less than 2.4 is graded B, and the case where Dvis is less than 2.3 is graded C.

3) Regarding preservation stability of image, evaluations of the following 4) and 5) were performed with a gray printed sample. In evaluation of image preservation stability, the density of step pattern was measured with densitometer X-rite 310 loading Status A Filter, and the change in density was measured with the point near Dvis=1.0 being the reference point.

4) Regarding light fastness, after finding the reflection spectrum at 380 to 730 nm by the measurement of density Ci at the maximum absorption wavelength just after printing with Spectroeye (manufactured by Gretag Macbeth), the image was irradiated with a xenon lamp (85,000 lux) for 10 days with a weather meter (manufactured by Atlas). After that, the reflection spectrum was again found by measuring density Cf at the maximum absorption wavelength, and light fastness was evaluated by finding the residual rate of dye [(Cf/Ci)×100].

The case where the residual rate of dye is 80% or more is graded A, the case of from 70 to 80% is graded B, and the case of less than 70% is graded C.

5) Regarding ozone-proofness, after finding the reflection spectrum at 380 to 730 nm by the measurement of density Ci at the maximum absorption wavelength just after printing with Spectroeye (manufactured by Gretag Macbeth), the image was exposed to ozone gas in a box set at ozone gas concentration of 5 ppm for 170 hours. After that, the reflection spectrum was again found by measuring density Cf at the maximum absorption wavelength, and ozone-proofness was evaluated by finding the residual rate of dye [(Cf/Ci)×100].

The ozone gas concentration in the box was set with an ozone gas monitor (model OZG-EM-01, manufactured by APPLICS).

The case where the residual rate of dye is 80% or more is graded A, the case of from 70 to 80% is graded B, and the case of less than 70% is graded C.

-   6) Regarding the hue balance in the deterioration of image     (hereinafter referred to as discoloration balance), CIEL*a*b* was     measured with Spectroeye (manufactured by Gretag Macbeth) before and     after evaluations 4) and 5). ΔEa*b* was found from the value before     exposure L_(i)*a_(i)*b_(i)* and the value after exposure     L_(f)*a_(f)*b_(f)* according to the following expression, and the     discoloration balance was evaluated on the basis of the following     criteria     ΔEa*b*=[(a _(i) *−a _(f)*)²+(b _(i) *−b _(f)*)²]^(1/2)     Criteria of Evaluation: -   A: ΔEa*b* is smaller than 20 in both tests of 4) and 5). -   B: ΔEa*b* is larger than 20 in either one test, or both of 4) and     5).

7) Regarding bronzing evaluation, black solid images were printed on photographic paper CRISPIA (high glossy paper) (manufactured by SETKO EPSON CORPORATION) on three conditions of 20° C. 40% RH, 35° C. 60% RH, and 35° C. 80% RH, and the images were allowed to stand overnight on the same conditions. Bronzing (metallic glossiness of the surfacc of the print) was evaluated by visual observation on the basis of the following criteria.

Criteria of Evaluation:

-   Grade A: Bronze glossiness is not observed at all. -   Grade B: Bronze glossiness is slightly observed in one condition of     three environmental conditions. -   Grade C: Bronze glossiness is slightly observed in two or more     conditions of three environmental conditions, and bronze glossiness     is clearly observed in one or more environmental conditions.

8) Regarding image blotting of black ink under high humidity condition, a checkered image having a line width of 0.2 mm and an interval between lines of 0.2 mm was made with imaging software Photoshop (manufactured by Adobe Systems Incorporated). A black-and-white checkered image sample comprising lines in black (R:0, R:0, B:0) and intervals between lines in white (R:255, G;255, B:255) was formed, and blotting of the image after being allowed to stand on the conditions of 25° C. 90% RH for 7 days was visually judged.

An image having no blotting in the white area of the checker is graded A, an image showing thickening of the line of the checker a little is graded B, and an image where the black dye clearly blotted on the white area is graded C.

The results obtained are shown in Table 2 below. TABLE 2 Light Ozone Discoloration Black Ink Hue Density Fastness Proofness Balance Bronzing Blotting of Image B-1 B A A A A A A B-2 B A A A A A A B-3 B A A A A A A B-4 B A A A A A A B-5 B A A A A A A B-6 B A A A A A A B-7 A A A A A A A B-8 (Comparison) B B A A A A A B-9 (Comparison) B B B B A B A B-10 (Comparison) B C B B A A A

As compared with the black inks (B-8, B-9, B-10) manufactured with the compound of formula (L-1) alone, the black ink compositions in the invention using water-soluble long wave dye L in addition to the compound of formula (L-1) shows that the density in black solid part is high without deteriorating discoloration balance, and bronze glossiness is restrained. It was found that by using water-soluble short wave dye S in addition to water-soluble long wave dye L, preferred black hue could be obtained.

When the same tests were carried out except for changing image-receiving sheets, almost the same results as in Table 2 were obtained. As the image-receiving sheets, Kassai (Photo Finish Pro, manufactured by Fuji Photo Film Co., Ltd.), Kassai (Photo Finish Advance, manufactured by Fuji Photo Film Co., Ltd.) double weight Hi, photographic paper CRISPIA (high glossy, manufactured by SEIKO EPSON CORPORATION), photographic paper (glossy, manufactured by SEIKO EPSON CORPORATION), Professional Photo Paper (manufactured by Canon Inc.), Super Photo Paper (manufactured by Canon Inc.), and Photolike QP (photographic image quality, manufactured by KONICA MINOLTA HOLDINGS, INC.) super double weight, were used.

Example 2

Preparation of Each Ink Composition:

Each ink composition was prepared by stirring at room temperature for 30 minutes the components based on the composition shown in Tables 3 and 4 below, and filtering the obtained solution through a membrane filter having opening of 1.0 μm. In Tables 3 and 4, the numerical value of each component is shown in wt % taking the mass of the ink composition as 100%, and “the rest” that shows the amount of water means the amount making 100% in total with the components other than water. TABLE 3 Y-1 Y-2 Y-3 Y-4 Y-5 M-1 M-2 M-3 M-4 M-5 C-1 C-2 C-3 C-4 C-5 YELLOW-1 5 4 YELLOW-2 5 YELLOW-3 5 YELLOW-4 1 YELLOW-5 1.5 YELLOW-6 1.5 YELLOW-7 0.5 MAGENTA-1 3.2 MAGENTA-2 3.2 MAGENTA-3 3.2 MAGENTA-4 3 MAGENTA-5 4 CYAN-1 5 4.5 4 CYAN-2 0.5 1 CYAN-3 CYAN-4 5 CYAN-5 5 Glycerol 12 12 12 12 12 10 10 10 10 10 12 12 12 12 12 Triethylene glycol 10 10 10 10 10 2 2 2 2 2 11 11 11 11 11 Propylene glycol 3 5 2 2 2 2 2 2 THGmBe 10 10 10 7 5 10 10 10 10 10 9 9 9 9 9 Sarfinol 465 (*1) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Urea 2 2 2 2 2 2.5 2.5 2.5 2.5 2.5 2 2 2 2 2 1,2-Hexanediol 2 3 3 2 5 5 2 2 2 2 2,5-Dimethyl-2,4-hexanediol 2 2 2 Triethanolamine 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.2 0.2 0.1 0.1 0.1 0.1 0.1 2-Pyrrolidone 4 4 4 4 4 PROXEL XL2 (*2) 0.3 0.3 0.3 0.3 0.3 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Water The The The The The The The The The The The The The The The rest rest rest rest rest rest rest rest rest rest rest rest rest rest rest Unit: wt % (*1) Manufactured by Air Products and Chemical, Inc. (*2) Manufactured by Abesia

TABLE 4 LM-1 LM-2 ML-3 LM-4 LM-5 LC-1 LC-2 LC-3 LC-4 LC-5 MAGENTA-1 1 MAGENTA-2 1 MAGENTA-3 1 MAGENTA-4 2 MAGENTA-5 2 CYAN-1 1.7 CYAN-2 1.7 CYAN-3 1.7 CYAN-4 1.7 CYAN-5 1.5 Glycerol 12 12 12 12 12 11 11 11 11 11 Triethylene glycol 10 10 10 10 8 4.5 4.5 2 4.5 3.5 Propylene glycol 2 2.5 1 TEGmBE 11 11 11 11 11 10 10 10 10 10 Sarfinol 465 (*1) 1 1 1 1 1 1 1 1 1 1 Urea 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 1,2-Hexanediol 3 3.4 3.4 3.4 3.4 2,5-Dimethyl-2,5-hexanediol 3 3.4 Triethanolamine 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 PROXEL XL2 (*2) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Water The The The The The The The The The The rest rest rest rest rest rest rest rest rest rest Unit: wt % *1: Manufactured by Air Products and Chemical, Inc. *2: Manufactured by Abesia (YELLOW-1):

(YELLOW-2):

(YELLOW-3):

Compound (YELLOW-1) can be synthesized according to the following method.

(1) Synthesis of Compound (YELLOW-1b):

Sodium hydrogencarbonate (25.5 g) and 150 ml of ion exchange water were heated at 40° C., and 25.0 g of cyanuric chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added in parts by 1/5 with every 10 minutes, and the mixture was stirred for 1 hour. The solution was dropped to a mixed solution (8° C.) of 52.8 ml of hydrazine and 47 ml of ion exchange water so that the inner temperature was not higher than 10° C. The inner temperature was raised to 50° C. and the solution was stirred for 30 minutes. The precipitated crystal was filtered to obtain 23.4 g of Compound b (YELLOW-1b) (hydrazine derivative, m.p. >300° C.). The yield was 94.7%.

(2) Synthesis of Compound (YELLOW-1c):

The compound (YELLOW-1b) (hydrazine derivative) (35.0 g) was suspended in 420 ml of ethylene glycol and stirred at inner temperature of 50° C. To the solution was added 95 ml of concentrated hydrochloric acid, and then 60.1 g of pivaloyl acetonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.), and the solution was stirred at 50° C. for 10 hours. Concentrated hydrochloric acid (95 ml) and 145 ml of methanol were added, and stirring was continued for further 8 hours. The temperature was lowered to room temperature, and the precipitated crystal was filtered to obtain 81.6 g of Compound c (5-aminopyrazole derivative, m.p. =233 to 235° C.). The yield was 94.2%. ¹H-NMR (DMSO-d6), δ value TMS standard: 1.2 to 1.3(18H, s)

(3) Synthesis of Compound (YELLOW-1e):

Compound d (manufactured by Tokyo Chemical Industry Co., Ltd.) (90.57 g) was suspended in 500 ml of H₂O, and 130 ml of concentrated hydrochloric acid was poured thereto and the inner temperature was lowered to 5° C. or lower. Subsequently, an aqueous solution containing 36.23 g of sodium nitrite and 70 ml of the solution was dropped thereto at inner temperature of from 4 to 6° C., and the mixed solution was stirred at inner temperature of 5° C. or lower for 30 minutes. After that, 159 g of sodium sulfite and 636 ml of H₂O were poured thereto while maintaining the inner temperature at 20° C. or lower, and then 250 ml of concentrated hydrochloric acid was poured thereto at inner temperature of 25° C., after stirring the solution for 1 hour at inner temperature of 90° C., the inner temperature was lowered to room temperature, and the reaction product was filtered and washed with 200 ml of water and dried to obtain 80.0 g of Compound e.

(4) Synthesis of Compound (YELLOW-1f):

After 28 ml of triethylamine was dropped into a suspension containing 23.3 g of Compound e and 209 ml. of ethanol at room temperature, 12.2 g of ethoxymethylene malononitrile (a product of ALDRICH) was added thereto in parts, and the suspension was refluxed for 3 hours. The inner temperature was lowered to room temperature, and the reaction solution was filtered, washed with 400 ml of isopropyl alcohol and dried, whereby 23.57 g of Compound f was obtained.

(5) Synthesis of Compound (YELLOW-1):

Into 32.4 ml of sulfuric acid was poured 145.56 ml of acetic acid at inner temperature of 4° C. or lower, subsequently 15.9 ml of 40% nitrosylsulfuric acid (a product of ALDRICH) was dropped thereto at inner temperature of 7° C. while stirring.

Compound (YELLOW-1f) (32.4 g) was added in parts to the above solution, after stirring the solution at inner temperature at 10° C. for 60 miniutes, 18.8 g of Compound C obtained by the addition of 1.83 g of urea to the reaction solution was suspended in 470 ml of methanol, and to this solution was dropwise added diazonium salt at inner temperature of higher than 0° C., and the solution was stirred at the same temperature for 30 minutes, the temperature of the reaction solution was increased to room temperature, and then the solution was filtered, washed with methanol, and then with H₂O to thereby obtain crude crystal. Subsequently, the crude crystal was suspended in 400 ml of methanol, and the suspension was stirred for 1 hour with refluxing, the temperature was lowered to room temperature, and the reaction solution was filtered, washed with methanol, with water, and then with methanol, dried at 75° C. overnight, whereby 34.4 g of free acid type crystal of Dye-11 was obtained. The obtained crystal was made a 10 wt % aqueous solution with KOH (at 25° C., pH: about 8.3), IPA was added to the solution at inner temperature at 50° C. and crystallized, cooled, filtered, washed with IPA, and dried, whereby 35 g of (YELLOW-1) (potassium salt) was obtained. λmax=436.4 nm (H₂O), ε: 3.53×10⁴ (dm³·cm/mol)

-   (YELLOW-5): C.I. Direct Yellow 132 -   (YELLOW-6): C.I. Direct Yellow 86 -   (YELLOW-7): C.I. Direct Yellow 58

As magenta dyes, the following (MAGENTA-1), (MAGENTA-2), (MAGENTA-3), (MAGENTA4), and (MAGENTA-5) were used.

(MAGENTA-1) can be synthesized according to the following method.

(1) Synthesis of Compound (MAGENTA-1a):

5-Amino-3-tert-butyl-4-cyanopyrazole (1) (24.1 g) (0.147 mol), 45 ml of concentrated hydrochloric acid, 30 ml of acetic acid, and 45 ml of propionic acid were stirred at inner temperature of 0° C., and 10.1 g (0.147 mol) of sodium nitrite dissolved in 20 ml of water was dropped to the above solution for 10 minutes. The solution was stirred for 30 minutes as it was. Coupler component (2) (84.7 g) (0.147 mol) was dissolved in 231 ml of methanesulfonic acid, 147 ml of acetic acid, and 221 ml of propionic acid, the solution was stirred at 0° C., and the above diazonium salt was added to the solution over 30 minutes. After the addition of the diazonium salt, the reaction solution was further stirred for 30 minutes, and then the reaction solution was gradually added to 2,250 ml of water added with 750 g of ice and stirred. Precipitated compound (MAGENTA-1a) was filtered by suction and isolated. Yield: 73.8 g, 85%.

(2) Synthesis of Compound (MAGENTA-1b):

To 21 g (35.5 mmol) of the compound (MAGENTA-1a) were added 26.6 g (157 mmol) of heterylizing agent (3), 21.7 g of potassium carbonate, and 147 ml of DMSO, and the mixture was heated at inner temperature of 92° C. and stirred for 4 hours while nitrogen bubbling. After termination of stirring, the temperature was lowered to room temperature, and the compound (MAGENTA-1b) precipitated from the reaction system was filtered by suction and isolated. This crude crystal was further dispersed in 3 liters of water to dissolve excessive amount of potassium carbonate, filtered by suction, whereby objective compound (MAGENTA-1b) was obtained. Yield: 20.0 g, 63.5%. λmax=558 nm (DMF solution), m/Z (POSI)=858.

(3) Synthesis of Compound (MAGENTA-1):

Compound (MAGENTA-1b) (2 g) (2.33 mmol) was dispersed in 7 g of Sulforan (manufactured by Tokyo Chemical Industry Co., Ltd.), and 1.7 g of NISSO SULFAN (sulfur trioxide, manufactured by NISSO METALLOCHEMICAL CO., LTD.) was dropped to the dispersion at inner temperature of 15° C. After termination of dropping, the dispersion was allowed to react for 2 hours at inner temperature of 70° C. After the reaction, the reaction solution was cooled to 20° C., and 2 ml of water was dropped to the reaction solution. The inner temperature was lowered to 5° C., and 3.3 ml of a 25 wt % sodium hydroxide aqueous solution was dropped thereto, and 0.8 ml of a 28 wt % methanol solution of sodium methoxide was further dropped. Further, 4 ml of methanol was dropped, and the precipitated inorganic salt was filtered and washed with 2 ml of methanol. Potassium acetate (2 g) and 5.6 ml of methanol were added to the filtrate, further 2.5 ml of ethanol was added to crystallize the dye, and the crystal was filtered by suction and washed with ethanol, whereby crude crystal of compound (MAGENTA-1) was obtained. The crude crystal containing the inorganic salt was purified by demineralization with Sephadex LH-20 gel chromatography (eluent, water/methanol: 1/1 (v/v), manufactured by Pharmacia) to obtain compound (MAGENTA-1). Yield: 2 g, 66%.

-   λmax (DMSO)=567.1 nm, ε=46,900

Compound (MAGENTA-2) and Compound (MAGENTA-3) can also be synthesized according to the similar synthesizing methods.

In Tables 3 and 4, as the cyan dyes, the following (CYAN-1), (CYAN-2), (CYAN-3), (CYAN-4) and (CYAN-5) were used.

One of rings A to D represents:

The remaining three represent:

* is bonding position of the phthalocyanine ring.

Two of rings A to D represent:

The remaining two represent:

* is bonding position of the phthalocyanine ring.

One of rings A to D represents:

The remaining three represent:

* is bonding position of the phthalocyanine ring.

* is bonding position of the phthalocyanine ring.

The mixture of the following Compounds I to III.

I. c=0, a+b=4

II. c=1, a+b=3

III. c=2, a+b=2

(CYAN-5): C.I. Direct Blue 199

Each of ink sets 1 to 10 was manufactured with each ink composition prepared above according to the combination as shown in Table 5 below. TABLE 5 Yellow Light Magenta Magenta Light Cyan Cyan Black Ink Set 1 Y-1 LM-1 M-1 LC-1 C-1 B-7 Ink Set 2 Y-2 LM-2 M-2 LC-2 C-2 B-7 Ink Set 3 Y-3 LM-3 M-3 LC-3 C-3 B-7 Ink Set 4 Y-4 LM-4 M-4 LC-4 C-4 B-7 Ink Set 5 Y-5 LM-5 M-5 LC-5 C-5 B-7 Ink Set 6 ICY32 (EPSON) ICLM32 (EPSON) ICM32 (EPSON) ICLC32 (EPSON) ICC32 (EPSON) B-7 Ink Set 7 BCI-7Y (Canon) BCI-7PM (Canon) BCI-7M (Canon) BCI-7PC (Canon) BCI-7C (Canon) B-7 Ink Set 8 (Comparison) Y-1 LM-1 M-1 LC-1 C-1 B-8 Ink Set 9 (Comparison) Y-2 LM-2 M-2 LC-2 C-2 B-8 Ink Set 10 (Comparison) Y-3 LM-3 M-3 LC-3 C-3 B-8

Each of these inks was filled in a corresponding ink cartridge of Ink Jet Printer PMG820 (manufactured by SEIKO EPSON CORPORATION). In ink set 6, genuine inks for PMG820 were used as they were except for the black ink, and in ink set 7, ink of each color of BCI-7 (manufactured by Canon Inc.) was extracted and filled in a corresponding ink cartridge for PMG800, and these ink cartridges were loaded on PMG800, and printing was performed.

Evaluation:

1) Regarding image preservation stability, a black solid image of R:0, G:0, B:0 was made with imaging software Photoshop (manufactured by Adobe Systems Incorporated), and a black solid image was printed. The evaluations of the following 2) and 3) were performed with the obtained image. In evaluation of image preservation stability, the density of step pattern was measured with densitometer X-rite 310 loading Status A Filter, and the change in density was measured.

2) Regarding light fastness, after measuring densities (D_(B), D_(G), D_(R)) Ci just after printing with X-rite 310, the image was irradiated with a xenon lamp (85,000 lux) for 10 days with a weather meter (manufactured by Atlas). After that, the densities Cf were measured, and light fastness was evaluated by finding the residual rate of dye [(Cf/Ci)×100].

The case where the residual rate of dye is 80% or more in all of D_(B), D_(G), D_(R) is graded A, the case of from 70 to 80% even at a part is graded B, and the case of less than 70% even at a part is graded C.

3) Regarding ozone-proofness, after measuring densities (D_(B), D_(G), D_(R)) Ci just after printing with X-rite 310, the image was exposed to ozone gas in a box set at ozone gas concentration of 5 ppm for 170 hours. After that, densities Cf were measured, and ozone-proofness was evaluated by finding the residual rate of dye [(Cf/Ci)×100].

The ozone gas concentration in the box was set with an ozone gas monitor (model OZG-EM-01, manufactured by APPLICS).

The case where the residual rate of dye is 80% or more in all of D_(B), D_(G), D_(R) is graded A, the case of from 70 to 80% even at a part is graded B, and the case of less than 70% even at a part is graded C.

4) Regarding image blotting of black ink under high humidity condition, the same black-and-white checkered image used in Example 1, a black-and-magenta checkered image formed by making the white area of the above image OD=1.0 of magenta, and a black-and-cyan checkered image formed by making the white area OD=1.0 of cyan, were prepared, and respective image samples were formed. With each image sample, blotting of each image after being allowed to stand on the conditions of 25° C. 90% RH for 7 days was visually judged.

An image having no blotting in the area between the lines of checker is graded A, an image where the hue of color correction dye is observed a little is graded B, and an image where the color correction dye is clearly blotted on the white area is graded C.

-   5) Regarding bronzing evaluation, the glossiness of the obtained     print was measured (measuring angle: 60°)with a gloss meter (PG-1M,     manufactured by Nippon Denshoku Industries Co., Ltd.). Printing was     performed on two environmental conditions of 20° C. 40% RH and     35° C. 60% RH. The obtained glossiness and the rising value computed     according to the following expression were taken as the reference     ofjudging the degree of generation of bronzing phenomenon, and     evaluated on the basis of the following criteria     Rising value=glossiness (printed matter)−glossiness (recording     medium)     Criteria of Evaluation: -   Grade A: Less than 15 -   Grade B: 15 or higher and less than 35 -   Grade C: 35 or higher and less than 55 -   Grade D: 55 or higher

The results of evaluation are shown in Table 6 below. TABLE 6 Light Ozone Blotting Black Ink Density Fastness Proofness Bronzing of Image Ink set 1 A A A A A Ink set 2 A A A A A Ink set 3 A A A A A Ink set 4 A A A A A Ink set 5 A A A A A Ink set 6 A A A A A Ink set 7 A A A A A Ink set 8 B A A A A (Comparison) Ink set 9 B A A A A (Comparison) Ink set 10 B A A A A (Comparison)

In the ink set using the black ink composition of the invention, in a black solid part of color print capable of ejecting yellow, magenta and cyan other than black ink, printed matters of high density black can be obtained without deteriorating light fastness, ozone-proofness, bronzing, and blotting of images.

When the same tests were carried out except for changing image-receiving sheets, almost the same results as in Table 6 were obtained As the image-receiving sheets, Kassai (Photo Finish Advance, manufactured by Fuji Photo Film Co., Ltd.) double weight Hi, Kassai (Photo Finish Pro, manufactured by Fuji Photo Film Co., Ltd.), photographic paper CRISPIA (high glossy, manufactured by SEIKO EPSON CORPORATION), photographic paper (glossy, manufactured by SEIKO EPSON CORPORATION), Professional Photo Paper (manufactured by Canon Inc.), Super Photo Paper (manufactured by Canon Inc.), and Photolike QP (photographic image quality, manufactured by KONICA MINOLTA HOLDINGS, INC.) super double weight, were used.

The ink according to the invention is fast to light and ozone gas, therefore, an image excellent in preservation stability by aging and having high density can be obtained.

The ink according to the invention can provide an image excellent in weatherproof and stability of hue and having high density.

Further, the ink according to the invention can provide an image restrained from bronze glossiness, free from blotting, and excellent in discoloration balance, and having high density.

The entire disclosure of each and every foreign patent application from which the benefit of foreign priority has been claimed in the present application is incorporated herein by reference, as if fully set forth. 

1. An ink composition, which comprises: at least two kinds of water-soluble dyes each having the maximum wavelength of an absorption spectrum in an aqueous solvent of from 550 to 700 nm, wherein at least one of the at least two kinds of water-soluble dyes is selected from the group consisting of a compound represented by formula (L-1), a salt of the compound represented by formula (L-1) and a compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups:

wherein A and B each independently represents an aromatic group that may be substituted or a heterocyclic group that may be substituted, and A is a monovalent group and B is a divalent group; T₁ and T₂ each independently represents ═CR₄₃— or —CR₄═, or either one represents a nitrogen atom and the other represents ═CR₄₃— or —CR₄₄═; V₁, R₄₃ and R₄₄ each independently represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclic oxycarbonyl group, an acyl group, a hydroxyl group, an alkoxyl group, an aryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, an amino group, an acylamino group, a ureido group, a sulfamoylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a heterocyclic sulfonylamino group, a nitro group, an alkylthio group, an arylthio group, a heterocyclic thio group, an alkylsulfonyl group, an arylsulfonyl group, a heterocyclic sulfonyl group, an alkylsulfinyl group, an arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group or a sulfo group, and each of these groups may further be substituted; R₄₁, R₄₂, R₄₃ and R₄₄ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group or a sulfamoyl group, and each of these groups may further have a substituted, provided that R₄₁ and R₄₂ do not represent a hydrogen atom at the same time, and R₄₃ and R₄₁, or R₄₁ and R₄₂ may be bonded to each other to form a 5- or 6-membered ring, provided that the compound represented by formula (L-1) contains at least one ionic hydrophilic group.
 2. The ink composition according to claim 1, wherein the compound represented by formula (L-1) is a compound represented by formula (L-2):

wherein X represents an N atom or ═CW₁—; W₁ represents an electron attracting group having a Hammett's substitution constant σp value of 0.20 or more; A, V₁, T₁, T₂, R₄ and R₄₂ respectively have the same meaning as A, V₁, T₁, T₂, R₄₁ and R₄₂ in formula (L-1); and W has the same meaning as V₁ in formula (L-1).
 3. The ink composition according to claim 2, wherein the compound represented by formula (L-2) is a compound represented by formula (L-3):

wherein V₁, W, X, T₁, T₂, R₄₁ and R₄₂ respectively have the same meaning as V₁, W, X, T₁, T₂, R₄₁ and R₄₂ in formula (L-2); and X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each represents a monovalent group.
 4. The ink composition according to claim 1, which comprises at least one compound represented by formula (L-1) and at least one compound represented by formula (L-4) different in structure from each other:

wherein R₄₃ has the same meaning as R₄₃ in formula (L-1); R₄₄ has the same meaning as R₄₄ in formula (L-1); R₄₅ and R₄₆ each has the same meaning as R₄₁ and R₄₂ in formula (L-1); R₄₁ and R₄₂ each has the same meaning as R₄₁ and R₄₂ in formula (L-1); W has the same meaning as V₁ in formula (L-1); and X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each represents a monovalent group.
 5. The ink composition according to claim 1, which comprises at least one compound represented by formula (L-1) and at least one compound represented by formula (L-5) different in structure from each other:

wherein R₄₃ has the same meaning as R₄₃ in formula (L-1); R₄₄ has the same meaning as R₄₄ in formula (L-1); R₄₅ and R₄₆ each has the same meaning as R₄₁ and R₄₂ in formula (L-1); R₄₁ and R₄₂ each has the same meaning as R₄₁ and R₄₂ in formula (L-1); W has the same meaning as V₁ in formula (L-1); W₁₁ represents an electron attracting group having a Hammett's substitution constant σp value of 0.20 or more; and X₁, X₂, X₃, X₄, X₅, X₆ and X₇ each represents a monovalent group.
 6. The ink composition according to claim 1, wherein the number of azo groups of the compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups is five or less.
 7. The ink composition according to claim 1, wherein the compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups contains one or more sulfonic acid group(s), one or more carboxyl group(s), or one or more sulfonic acid group(s) and one or more carboxyl group(s).
 8. The ink composition according to claim 1, wherein the compound having a naphthalene ring substituted with at least one hydroxyl group and three or more azo groups is a compound selected from the group consisting of a compound represented by any of formulae (L-6), (L-6a), (L-7) and (L-8) and a salt of the compound represented by any of formulae (L-6), (L-6a), (L-7) and (L-8):

wherein R₁₁ and R₁₂ each independently represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a sulfamoyl group that may be substituted with an alkyl group or a phenyl group; a phosphoric acid group; a nitro group; an acyl group; a ureido group; an alkyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group or an alkoxyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms or an acylamino group that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group or a carboxyl group; E represents a phenyl group or a naphthyl group, which may be substituted with a halogen atom; a cyano group; a carboxyl group; a sulfo group; a sulfamoyl group that may be substituted with an alkyl group or a phenyl group; a phosphoric acid group; a nitro group; an acyl group; a ureido group; an alkyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group or an alkoxyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms or an acylamino group that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group or a carboxyl group; and n₁ represents 0 or 1;

wherein A represents formula (L-6a-1), and the substitution position of A is the m- or p-position to the azo group; R¹ and R² each independently represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a sulfamoyl group; an N-alkylaminosulfonyl group; an N-phenylamino-sulfonyl group; a phospho group; a nitro group; an acyl group; a ureido group; an alkyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group or an alkoxyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group or a carboxyl group; or an acylamino group that may be substituted with an alkoxyl group having from 1 to 4 carbon atoms, a sulfo group or a carboxyl group; R³ and R⁴ each independently represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a nitro group; an alkyl group having from 1 to 4 carbon atoms; a hydroxyl group; or an alkoxyl group having from 1 to 4 carbon atoms that may be substituted with an alkoxyl group having from 1 to 4 carbon atoms or a sulfo group; and n represents 0 or 1;

wherein R⁵ represents a cyano group; a carboxyl group; an alkyl group having from 1 to 4 carbon atoms; an alkoxycarbonyl gruop having from 1 to 4 carbon atoms; or a phenyl group; R⁶, R⁷ and R⁸ each independently represents a hydrogen atom; a halogen atom; a cyano group; a carboxyl group; a sulfo group; a nitro group; an alkyl group having from 1 to 4 carbon atoms; an alkoxyl group having from 1 to 4 carbon atoms that may be substitutted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms or a sulfo group; or an acylamino group that may be substituted with a hydroxyl group, an alkoxyl group having from 1 to 4 carbon atoms or a sulfo group;

wherein G and J each independently represents a phenyl group or a naphthyl group that may be substituted, or a 5- or 6-membered aromatic heterocyclic group bonding to the azo group via a carbon atom, and each of G and J contains at least one or more carboxy] group(s) or sulfo group(s); one of X and Y represents a hydroxyl group, and the other represents an amino group; and l₂, m₂ and n₂ each independently represents 1 or 2;

wherein R₂₁ represents a phenyl group having a substituent, or a naphthyl group having a substituent; R₂₂ represents a phenylene group having a substituent, or a naphthylene group having a substituent; R₂₃ represents a 5- to 7-membered heterocyclic group having at least one double bond and a substituent; and the substituents in R₂₁, R₂₂ and R₂₃ are each independently selected from the group consisting of OH, SO₃H, PO₃H₂, CO₂H, NO₂, NH₂, an alkyl group having from 1 to 4 carbon atoms, an alkyl group having from 1 to 4 carbon atoms and a substituent, an alkoxyl group having from 1 to 4 carbon atoms, an alkoxyl group having from 1 to 4 carbon atoms and a substituent, an amino group, an amino group having a substituent and a phenyl group having a substituent.
 9. An ink composition, which comprises: at least two kinds of water-soluble dyes each having the maximum wavelength of an absorption spectrum in an aqueous solvent of from 550 to 700 nm, wherein the at least two kinds of water-soluble dyes include: at least one compound selected from the group consisting of a compound represented by formula (L-1) according to claim 1, a compound represented by formula (L-2) according to claim 2, a compound represented by formula (L-3) according to claim 3, a compound represented by formula (L-4) according to claim 4 and a compound represented by formula (L-5) according to claim 5; and at least one compound selected from the group consisting of a compound represented by any of formulae (L-6), (L-6a), (L-7) and (L-8) and a salt of the compound represented by any of formulae (L-6), (L-6a), (L-7) and (L-8) according to claim
 8. 10. The ink composition according to claim 8, wherein the compound represented by formula (L-8) is a compound represented by formula (L-9):

wherein R₃₁ to R₃₉ each independently represents a group selected from the group consisting of H, OH, SO₃H, POH₂, CO₂H, NO₂ and NH₂.
 11. The ink composition according to claim 1, which further comprises at least one kind of water-soluble dye having the maximum wavelength of an absorption spectrum in an aqueous solvent of from 400 to 520 nm.
 12. The ink composition according to claim 11, which comprises the at least one kind of water-soluble dye having the maximum wavelength of an absorption spectrum in an aqueous solvent of from 400 to 520 nm in an amount of from 0.1 to 4 mass %.
 13. An ink set, which comprises at least one kind of an ink composition according to claim
 1. 14. A recording method, which comprises: applying an ink composition according to claim 1 to a recording medium to conduct recording.
 15. A recording method, which comprises: loading an ink set according to claim 13 on a recording apparatus; and applying an ink from the recording apparatus to a recording medium to conduct recording.
 16. The recording method according to claim 14, which comprises: ejecting the ink composition from an ink jet nozzle to a recording medium to conduct recording. 